Submission #296436

# Submission time Handle Problem Language Result Execution time Memory
296436 2020-09-10T14:39:20 Z morato Traffic (IOI10_traffic) C++17
100 / 100
1253 ms 170744 KB
#include <bits/stdc++.h>
using namespace std;

const int maxn = 1e6 + 5;

vector<int> adj[maxn];
int64_t p[maxn], h[maxn], sub[maxn];

void dfs(int v, int _p = -1) {
  sub[v] = p[v];
  for (int u : adj[v]) if (u != _p) {
    dfs(u, v);
    sub[v] += sub[u];
    h[v] = max(h[v], sub[u]);
  }
}

int LocateCentre(int N, int P[], int S[], int D[]) {
  int64_t tot = 0;
  for (int i = 0; i < N; i++) {
    p[i] = 1ll * P[i];
    tot += p[i];
  }
  for (int i = 0; i < N - 1; i++) {
    adj[S[i]].push_back(D[i]);
    adj[D[i]].push_back(S[i]);
  }
  dfs(0);
  assert(sub[0] == tot);
  int ans = 0;
  int64_t heavy = h[0];
  for (int i = 1; i < N; i++) {
    h[i] = max(h[i], sub[0] - sub[i]);
    if (h[i] < heavy) {
      heavy = h[i];
      ans = i;
    }
  }
  return ans;
}
# Verdict Execution time Memory Grader output
1 Correct 15 ms 23808 KB Output is correct
2 Correct 15 ms 23808 KB Output is correct
3 Correct 15 ms 23808 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 16 ms 23808 KB Output is correct
7 Correct 16 ms 23808 KB Output is correct
8 Correct 16 ms 23808 KB Output is correct
9 Correct 16 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 18 ms 23808 KB Output is correct
12 Correct 17 ms 23808 KB Output is correct
13 Correct 18 ms 23808 KB Output is correct
14 Correct 16 ms 23808 KB Output is correct
15 Correct 16 ms 23896 KB Output is correct
16 Correct 17 ms 23808 KB Output is correct
17 Correct 17 ms 23808 KB Output is correct
18 Correct 17 ms 23808 KB Output is correct
19 Correct 17 ms 23808 KB Output is correct
20 Correct 16 ms 23808 KB Output is correct
21 Correct 16 ms 23872 KB Output is correct
22 Correct 16 ms 23808 KB Output is correct
23 Correct 17 ms 23808 KB Output is correct
24 Correct 18 ms 23808 KB Output is correct
25 Correct 17 ms 23808 KB Output is correct
26 Correct 18 ms 23808 KB Output is correct
27 Correct 19 ms 23936 KB Output is correct
28 Correct 16 ms 23936 KB Output is correct
29 Correct 16 ms 23936 KB Output is correct
30 Correct 17 ms 23936 KB Output is correct
31 Correct 17 ms 23936 KB Output is correct
32 Correct 17 ms 23936 KB Output is correct
33 Correct 17 ms 24064 KB Output is correct
34 Correct 17 ms 23808 KB Output is correct
35 Correct 16 ms 23936 KB Output is correct
36 Correct 17 ms 23936 KB Output is correct
37 Correct 17 ms 23936 KB Output is correct
38 Correct 16 ms 23928 KB Output is correct
39 Correct 16 ms 23936 KB Output is correct
40 Correct 15 ms 23988 KB Output is correct
41 Correct 16 ms 24024 KB Output is correct
42 Correct 19 ms 24056 KB Output is correct
43 Correct 15 ms 23808 KB Output is correct
44 Correct 15 ms 23840 KB Output is correct
45 Correct 15 ms 23808 KB Output is correct
46 Correct 15 ms 23820 KB Output is correct
47 Correct 17 ms 23808 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 15 ms 23808 KB Output is correct
2 Correct 15 ms 23808 KB Output is correct
3 Correct 15 ms 23808 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 16 ms 23808 KB Output is correct
7 Correct 16 ms 23808 KB Output is correct
8 Correct 16 ms 23808 KB Output is correct
9 Correct 16 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 18 ms 23808 KB Output is correct
12 Correct 17 ms 23808 KB Output is correct
13 Correct 18 ms 23808 KB Output is correct
14 Correct 16 ms 23808 KB Output is correct
15 Correct 16 ms 23896 KB Output is correct
16 Correct 17 ms 23808 KB Output is correct
17 Correct 17 ms 23808 KB Output is correct
18 Correct 17 ms 23808 KB Output is correct
19 Correct 17 ms 23808 KB Output is correct
20 Correct 16 ms 23808 KB Output is correct
21 Correct 16 ms 23872 KB Output is correct
22 Correct 16 ms 23808 KB Output is correct
23 Correct 17 ms 23808 KB Output is correct
24 Correct 18 ms 23808 KB Output is correct
25 Correct 17 ms 23808 KB Output is correct
26 Correct 18 ms 23808 KB Output is correct
27 Correct 19 ms 23936 KB Output is correct
28 Correct 16 ms 23936 KB Output is correct
29 Correct 16 ms 23936 KB Output is correct
30 Correct 17 ms 23936 KB Output is correct
31 Correct 17 ms 23936 KB Output is correct
32 Correct 17 ms 23936 KB Output is correct
33 Correct 17 ms 24064 KB Output is correct
34 Correct 17 ms 23808 KB Output is correct
35 Correct 16 ms 23936 KB Output is correct
36 Correct 17 ms 23936 KB Output is correct
37 Correct 17 ms 23936 KB Output is correct
38 Correct 16 ms 23928 KB Output is correct
39 Correct 16 ms 23936 KB Output is correct
40 Correct 15 ms 23988 KB Output is correct
41 Correct 16 ms 24024 KB Output is correct
42 Correct 19 ms 24056 KB Output is correct
43 Correct 15 ms 23808 KB Output is correct
44 Correct 15 ms 23840 KB Output is correct
45 Correct 15 ms 23808 KB Output is correct
46 Correct 15 ms 23820 KB Output is correct
47 Correct 17 ms 23808 KB Output is correct
48 Correct 15 ms 23808 KB Output is correct
49 Correct 15 ms 23808 KB Output is correct
50 Correct 15 ms 23808 KB Output is correct
51 Correct 15 ms 23808 KB Output is correct
52 Correct 16 ms 23936 KB Output is correct
53 Correct 17 ms 23808 KB Output is correct
54 Correct 17 ms 23808 KB Output is correct
55 Correct 17 ms 23808 KB Output is correct
56 Correct 16 ms 23808 KB Output is correct
57 Correct 17 ms 23808 KB Output is correct
58 Correct 16 ms 23808 KB Output is correct
59 Correct 19 ms 23808 KB Output is correct
60 Correct 17 ms 23808 KB Output is correct
61 Correct 20 ms 23808 KB Output is correct
62 Correct 16 ms 23808 KB Output is correct
63 Correct 16 ms 23808 KB Output is correct
64 Correct 18 ms 23936 KB Output is correct
65 Correct 19 ms 23808 KB Output is correct
66 Correct 16 ms 23808 KB Output is correct
67 Correct 17 ms 23808 KB Output is correct
68 Correct 54 ms 31096 KB Output is correct
69 Correct 94 ms 38392 KB Output is correct
70 Correct 15 ms 23808 KB Output is correct
71 Correct 97 ms 45856 KB Output is correct
72 Correct 171 ms 53160 KB Output is correct
73 Correct 154 ms 60536 KB Output is correct
74 Correct 178 ms 67836 KB Output is correct
75 Correct 209 ms 75256 KB Output is correct
76 Correct 259 ms 82680 KB Output is correct
77 Correct 304 ms 89956 KB Output is correct
78 Correct 300 ms 97300 KB Output is correct
79 Correct 322 ms 104720 KB Output is correct
80 Correct 346 ms 111972 KB Output is correct
81 Correct 16 ms 23808 KB Output is correct
82 Correct 386 ms 119544 KB Output is correct
83 Correct 416 ms 126712 KB Output is correct
84 Correct 445 ms 134136 KB Output is correct
85 Correct 460 ms 141616 KB Output is correct
86 Correct 482 ms 148728 KB Output is correct
87 Correct 522 ms 156152 KB Output is correct
88 Correct 539 ms 163748 KB Output is correct
89 Correct 571 ms 170744 KB Output is correct
90 Correct 17 ms 23808 KB Output is correct
91 Correct 16 ms 23808 KB Output is correct
92 Correct 16 ms 23808 KB Output is correct
93 Correct 17 ms 23808 KB Output is correct
94 Correct 16 ms 23808 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 15 ms 23808 KB Output is correct
2 Correct 15 ms 23808 KB Output is correct
3 Correct 15 ms 23808 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 16 ms 23808 KB Output is correct
7 Correct 16 ms 23808 KB Output is correct
8 Correct 16 ms 23808 KB Output is correct
9 Correct 16 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 18 ms 23808 KB Output is correct
12 Correct 17 ms 23808 KB Output is correct
13 Correct 18 ms 23808 KB Output is correct
14 Correct 16 ms 23808 KB Output is correct
15 Correct 16 ms 23896 KB Output is correct
16 Correct 17 ms 23808 KB Output is correct
17 Correct 17 ms 23808 KB Output is correct
18 Correct 17 ms 23808 KB Output is correct
19 Correct 17 ms 23808 KB Output is correct
20 Correct 16 ms 23808 KB Output is correct
21 Correct 16 ms 23872 KB Output is correct
22 Correct 16 ms 23808 KB Output is correct
23 Correct 17 ms 23808 KB Output is correct
24 Correct 18 ms 23808 KB Output is correct
25 Correct 17 ms 23808 KB Output is correct
26 Correct 18 ms 23808 KB Output is correct
27 Correct 19 ms 23936 KB Output is correct
28 Correct 16 ms 23936 KB Output is correct
29 Correct 16 ms 23936 KB Output is correct
30 Correct 17 ms 23936 KB Output is correct
31 Correct 17 ms 23936 KB Output is correct
32 Correct 17 ms 23936 KB Output is correct
33 Correct 17 ms 24064 KB Output is correct
34 Correct 17 ms 23808 KB Output is correct
35 Correct 16 ms 23936 KB Output is correct
36 Correct 17 ms 23936 KB Output is correct
37 Correct 17 ms 23936 KB Output is correct
38 Correct 16 ms 23928 KB Output is correct
39 Correct 16 ms 23936 KB Output is correct
40 Correct 15 ms 23988 KB Output is correct
41 Correct 16 ms 24024 KB Output is correct
42 Correct 19 ms 24056 KB Output is correct
43 Correct 15 ms 23808 KB Output is correct
44 Correct 15 ms 23840 KB Output is correct
45 Correct 15 ms 23808 KB Output is correct
46 Correct 15 ms 23820 KB Output is correct
47 Correct 17 ms 23808 KB Output is correct
48 Correct 16 ms 23808 KB Output is correct
49 Correct 16 ms 23808 KB Output is correct
50 Correct 17 ms 23808 KB Output is correct
51 Correct 17 ms 23808 KB Output is correct
52 Correct 17 ms 23808 KB Output is correct
53 Correct 17 ms 23808 KB Output is correct
54 Correct 16 ms 23808 KB Output is correct
55 Correct 16 ms 23808 KB Output is correct
56 Correct 17 ms 23808 KB Output is correct
57 Correct 16 ms 23808 KB Output is correct
58 Correct 16 ms 23808 KB Output is correct
59 Correct 16 ms 23808 KB Output is correct
60 Correct 16 ms 23808 KB Output is correct
61 Correct 16 ms 23808 KB Output is correct
62 Correct 16 ms 23808 KB Output is correct
63 Correct 16 ms 23808 KB Output is correct
64 Correct 16 ms 23808 KB Output is correct
65 Correct 16 ms 23808 KB Output is correct
66 Correct 16 ms 23808 KB Output is correct
67 Correct 17 ms 23808 KB Output is correct
68 Correct 16 ms 23808 KB Output is correct
69 Correct 17 ms 23808 KB Output is correct
70 Correct 17 ms 23808 KB Output is correct
71 Correct 16 ms 23808 KB Output is correct
72 Correct 16 ms 23808 KB Output is correct
73 Correct 18 ms 23936 KB Output is correct
74 Correct 16 ms 23808 KB Output is correct
75 Correct 16 ms 23808 KB Output is correct
76 Correct 17 ms 23808 KB Output is correct
77 Correct 16 ms 23808 KB Output is correct
78 Correct 16 ms 23808 KB Output is correct
79 Correct 16 ms 23912 KB Output is correct
80 Correct 17 ms 23808 KB Output is correct
81 Correct 16 ms 23808 KB Output is correct
82 Correct 17 ms 23936 KB Output is correct
83 Correct 16 ms 23936 KB Output is correct
84 Correct 17 ms 23936 KB Output is correct
85 Correct 17 ms 23936 KB Output is correct
86 Correct 16 ms 23936 KB Output is correct
87 Correct 17 ms 23936 KB Output is correct
88 Correct 19 ms 24064 KB Output is correct
89 Correct 17 ms 23936 KB Output is correct
90 Correct 18 ms 23936 KB Output is correct
91 Correct 17 ms 23936 KB Output is correct
92 Correct 16 ms 23808 KB Output is correct
93 Correct 17 ms 23936 KB Output is correct
94 Correct 16 ms 23936 KB Output is correct
95 Correct 17 ms 23936 KB Output is correct
96 Correct 16 ms 23808 KB Output is correct
97 Correct 17 ms 23808 KB Output is correct
98 Correct 16 ms 23808 KB Output is correct
99 Correct 17 ms 23808 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 15 ms 23808 KB Output is correct
2 Correct 15 ms 23808 KB Output is correct
3 Correct 15 ms 23808 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 16 ms 23808 KB Output is correct
7 Correct 16 ms 23808 KB Output is correct
8 Correct 16 ms 23808 KB Output is correct
9 Correct 16 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 18 ms 23808 KB Output is correct
12 Correct 17 ms 23808 KB Output is correct
13 Correct 18 ms 23808 KB Output is correct
14 Correct 16 ms 23808 KB Output is correct
15 Correct 16 ms 23896 KB Output is correct
16 Correct 17 ms 23808 KB Output is correct
17 Correct 17 ms 23808 KB Output is correct
18 Correct 17 ms 23808 KB Output is correct
19 Correct 17 ms 23808 KB Output is correct
20 Correct 16 ms 23808 KB Output is correct
21 Correct 16 ms 23872 KB Output is correct
22 Correct 16 ms 23808 KB Output is correct
23 Correct 17 ms 23808 KB Output is correct
24 Correct 18 ms 23808 KB Output is correct
25 Correct 17 ms 23808 KB Output is correct
26 Correct 18 ms 23808 KB Output is correct
27 Correct 19 ms 23936 KB Output is correct
28 Correct 16 ms 23936 KB Output is correct
29 Correct 16 ms 23936 KB Output is correct
30 Correct 17 ms 23936 KB Output is correct
31 Correct 17 ms 23936 KB Output is correct
32 Correct 17 ms 23936 KB Output is correct
33 Correct 17 ms 24064 KB Output is correct
34 Correct 17 ms 23808 KB Output is correct
35 Correct 16 ms 23936 KB Output is correct
36 Correct 17 ms 23936 KB Output is correct
37 Correct 17 ms 23936 KB Output is correct
38 Correct 16 ms 23928 KB Output is correct
39 Correct 16 ms 23936 KB Output is correct
40 Correct 15 ms 23988 KB Output is correct
41 Correct 16 ms 24024 KB Output is correct
42 Correct 19 ms 24056 KB Output is correct
43 Correct 15 ms 23808 KB Output is correct
44 Correct 15 ms 23840 KB Output is correct
45 Correct 15 ms 23808 KB Output is correct
46 Correct 15 ms 23820 KB Output is correct
47 Correct 17 ms 23808 KB Output is correct
48 Correct 15 ms 23808 KB Output is correct
49 Correct 15 ms 23808 KB Output is correct
50 Correct 15 ms 23808 KB Output is correct
51 Correct 15 ms 23808 KB Output is correct
52 Correct 16 ms 23936 KB Output is correct
53 Correct 17 ms 23808 KB Output is correct
54 Correct 17 ms 23808 KB Output is correct
55 Correct 17 ms 23808 KB Output is correct
56 Correct 16 ms 23808 KB Output is correct
57 Correct 17 ms 23808 KB Output is correct
58 Correct 16 ms 23808 KB Output is correct
59 Correct 19 ms 23808 KB Output is correct
60 Correct 17 ms 23808 KB Output is correct
61 Correct 20 ms 23808 KB Output is correct
62 Correct 16 ms 23808 KB Output is correct
63 Correct 16 ms 23808 KB Output is correct
64 Correct 18 ms 23936 KB Output is correct
65 Correct 19 ms 23808 KB Output is correct
66 Correct 16 ms 23808 KB Output is correct
67 Correct 17 ms 23808 KB Output is correct
68 Correct 54 ms 31096 KB Output is correct
69 Correct 94 ms 38392 KB Output is correct
70 Correct 15 ms 23808 KB Output is correct
71 Correct 97 ms 45856 KB Output is correct
72 Correct 171 ms 53160 KB Output is correct
73 Correct 154 ms 60536 KB Output is correct
74 Correct 178 ms 67836 KB Output is correct
75 Correct 209 ms 75256 KB Output is correct
76 Correct 259 ms 82680 KB Output is correct
77 Correct 304 ms 89956 KB Output is correct
78 Correct 300 ms 97300 KB Output is correct
79 Correct 322 ms 104720 KB Output is correct
80 Correct 346 ms 111972 KB Output is correct
81 Correct 16 ms 23808 KB Output is correct
82 Correct 386 ms 119544 KB Output is correct
83 Correct 416 ms 126712 KB Output is correct
84 Correct 445 ms 134136 KB Output is correct
85 Correct 460 ms 141616 KB Output is correct
86 Correct 482 ms 148728 KB Output is correct
87 Correct 522 ms 156152 KB Output is correct
88 Correct 539 ms 163748 KB Output is correct
89 Correct 571 ms 170744 KB Output is correct
90 Correct 17 ms 23808 KB Output is correct
91 Correct 16 ms 23808 KB Output is correct
92 Correct 16 ms 23808 KB Output is correct
93 Correct 17 ms 23808 KB Output is correct
94 Correct 16 ms 23808 KB Output is correct
95 Correct 16 ms 23808 KB Output is correct
96 Correct 16 ms 23808 KB Output is correct
97 Correct 17 ms 23808 KB Output is correct
98 Correct 17 ms 23808 KB Output is correct
99 Correct 17 ms 23808 KB Output is correct
100 Correct 17 ms 23808 KB Output is correct
101 Correct 16 ms 23808 KB Output is correct
102 Correct 16 ms 23808 KB Output is correct
103 Correct 17 ms 23808 KB Output is correct
104 Correct 16 ms 23808 KB Output is correct
105 Correct 16 ms 23808 KB Output is correct
106 Correct 16 ms 23808 KB Output is correct
107 Correct 16 ms 23808 KB Output is correct
108 Correct 16 ms 23808 KB Output is correct
109 Correct 16 ms 23808 KB Output is correct
110 Correct 16 ms 23808 KB Output is correct
111 Correct 16 ms 23808 KB Output is correct
112 Correct 16 ms 23808 KB Output is correct
113 Correct 16 ms 23808 KB Output is correct
114 Correct 17 ms 23808 KB Output is correct
115 Correct 16 ms 23808 KB Output is correct
116 Correct 17 ms 23808 KB Output is correct
117 Correct 17 ms 23808 KB Output is correct
118 Correct 16 ms 23808 KB Output is correct
119 Correct 16 ms 23808 KB Output is correct
120 Correct 18 ms 23936 KB Output is correct
121 Correct 16 ms 23808 KB Output is correct
122 Correct 16 ms 23808 KB Output is correct
123 Correct 17 ms 23808 KB Output is correct
124 Correct 16 ms 23808 KB Output is correct
125 Correct 16 ms 23808 KB Output is correct
126 Correct 16 ms 23912 KB Output is correct
127 Correct 17 ms 23808 KB Output is correct
128 Correct 16 ms 23808 KB Output is correct
129 Correct 17 ms 23936 KB Output is correct
130 Correct 16 ms 23936 KB Output is correct
131 Correct 17 ms 23936 KB Output is correct
132 Correct 17 ms 23936 KB Output is correct
133 Correct 16 ms 23936 KB Output is correct
134 Correct 17 ms 23936 KB Output is correct
135 Correct 19 ms 24064 KB Output is correct
136 Correct 17 ms 23936 KB Output is correct
137 Correct 18 ms 23936 KB Output is correct
138 Correct 17 ms 23936 KB Output is correct
139 Correct 16 ms 23808 KB Output is correct
140 Correct 17 ms 23936 KB Output is correct
141 Correct 16 ms 23936 KB Output is correct
142 Correct 17 ms 23936 KB Output is correct
143 Correct 16 ms 23808 KB Output is correct
144 Correct 17 ms 23808 KB Output is correct
145 Correct 16 ms 23808 KB Output is correct
146 Correct 17 ms 23808 KB Output is correct
147 Correct 17 ms 23808 KB Output is correct
148 Correct 16 ms 23808 KB Output is correct
149 Correct 16 ms 23936 KB Output is correct
150 Correct 16 ms 23808 KB Output is correct
151 Correct 17 ms 23808 KB Output is correct
152 Correct 16 ms 23808 KB Output is correct
153 Correct 16 ms 23808 KB Output is correct
154 Correct 17 ms 23808 KB Output is correct
155 Correct 16 ms 23808 KB Output is correct
156 Correct 17 ms 23936 KB Output is correct
157 Correct 17 ms 23808 KB Output is correct
158 Correct 16 ms 23808 KB Output is correct
159 Correct 16 ms 23808 KB Output is correct
160 Correct 17 ms 23808 KB Output is correct
161 Correct 16 ms 23808 KB Output is correct
162 Correct 16 ms 23808 KB Output is correct
163 Correct 16 ms 23808 KB Output is correct
164 Correct 16 ms 23808 KB Output is correct
165 Correct 16 ms 23808 KB Output is correct
166 Correct 17 ms 23808 KB Output is correct
167 Correct 16 ms 23808 KB Output is correct
168 Correct 17 ms 23808 KB Output is correct
169 Correct 17 ms 23936 KB Output is correct
170 Correct 18 ms 23808 KB Output is correct
171 Correct 54 ms 28028 KB Output is correct
172 Correct 102 ms 32248 KB Output is correct
173 Correct 157 ms 36472 KB Output is correct
174 Correct 221 ms 40824 KB Output is correct
175 Correct 279 ms 45048 KB Output is correct
176 Correct 341 ms 49444 KB Output is correct
177 Correct 399 ms 53624 KB Output is correct
178 Correct 485 ms 57884 KB Output is correct
179 Correct 538 ms 62204 KB Output is correct
180 Correct 16 ms 23808 KB Output is correct
181 Correct 610 ms 66288 KB Output is correct
182 Correct 666 ms 70648 KB Output is correct
183 Correct 720 ms 74820 KB Output is correct
184 Correct 799 ms 79096 KB Output is correct
185 Correct 864 ms 83372 KB Output is correct
186 Correct 941 ms 87544 KB Output is correct
187 Correct 991 ms 91768 KB Output is correct
188 Correct 1079 ms 96036 KB Output is correct
189 Correct 1130 ms 100344 KB Output is correct
190 Correct 1198 ms 104444 KB Output is correct
191 Correct 16 ms 23936 KB Output is correct
192 Correct 1253 ms 108808 KB Output is correct
193 Correct 279 ms 95992 KB Output is correct
194 Correct 548 ms 168308 KB Output is correct
195 Correct 16 ms 23808 KB Output is correct
196 Correct 17 ms 23808 KB Output is correct
197 Correct 17 ms 23808 KB Output is correct
198 Correct 16 ms 23932 KB Output is correct