#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 200000
int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }
int dist(int a, int b, int c) {
return max(max(a, b), c) - min(min(a, b), c);
}
int *ej[N], eo[N], n;
void append(int i, int j) {
int o = eo[i]++;
if (o >= 2 && (o & o - 1) == 0)
ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]);
ej[i][o] = j;
}
int ta[N], tb[N], c;
int rr[N], sz[N];
void dfs1(int p, int i) {
static int time;
int o, centroid;
ta[i] = time++;
sz[i] = 1, centroid = 1;
for (o = eo[i]; o--; ) {
int j = ej[i][o];
if (j != p) {
dfs1(i, j);
sz[i] += sz[j];
if (sz[j] * 2 > n)
centroid = 0;
}
}
if ((n - sz[i]) * 2 > n)
centroid = 0;
if (centroid)
c = i;
tb[i] = time;
}
void dfs2(int p, int r, int i) {
int o;
rr[i] = r, sz[i] = 1;
for (o = eo[i]; o--; ) {
int j = ej[i][o];
if (j != p) {
dfs2(i, r, j);
sz[i] += sz[j];
}
}
}
int main() {
static int rr_[N], dp1[N], dp2[N], dq1[N], dq2[N];
int h, i, j, s, o, ans;
scanf("%d", &n);
for (i = 0; i < n; i++)
ej[i] = (int *) malloc(2 * sizeof *ej[i]);
for (h = 0; h < n - 1; h++) {
scanf("%d%d", &i, &j), i--, j--;
append(i, j), append(j, i);
}
dfs1(-1, 0);
for (o = eo[c]; o--; ) {
j = ej[c][o];
dfs2(c, j, j);
}
memset(rr_, -1, n * sizeof *rr_);
for (i = 0; i < n; i++)
if (i != c) {
if (rr_[sz[i]] == -1)
rr_[sz[i]] = rr[i];
else if (rr_[sz[i]] != rr[i])
rr_[sz[i]] = -2;
}
for (s = 0; s < n; s++) {
dp1[s] = s == 0 ? -1 : dp1[s - 1], dp2[s] = s == 0 ? -1 : dp2[s - 1];
if (rr_[s] != -1) {
if (dp1[s] == -1 || rr_[dp1[s]] != rr_[s])
dp2[s] = dp1[s];
dp1[s] = s;
}
}
for (s = n - 1; s >= 0; s--) {
dq1[s] = s + 1 == n ? n : dq1[s + 1], dq2[s] = s + 1 == n ? n : dq2[s + 1];
if (rr_[s] != -1) {
if (dq1[s] == n || rr_[dq1[s]] != rr_[s])
dq2[s] = dq1[s];
dq1[s] = s;
}
}
ans = n + 1;
for (i = 0; i < n; i++)
if (i != c) {
int s, s_;
if (i != rr[i])
ans = min(ans, dist(n - sz[rr[i]], sz[rr[i]] - sz[i], sz[i]));
s = (n - sz[i]) / 2;
if ((s_ = dp1[s]) != -1 && rr_[s_] != rr[i])
ans = min(ans, dist(sz[i], s_, n - sz[i] - s_));
else if ((s_ = dp2[s]) != -1)
ans = min(ans, dist(sz[i], s_, n - sz[i] - s_));
if ((s_ = dq1[s]) != n && rr_[s_] != rr[i])
ans = min(ans, dist(sz[i], s_, n - sz[i] - s_));
else if ((s_ = dq2[s]) != n)
ans = min(ans, dist(sz[i], s_, n - sz[i] - s_));
}
printf("%d\n", ans);
return 0;
}
Compilation message
papricice.c: In function 'append':
papricice.c:19:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
19 | if (o >= 2 && (o & o - 1) == 0)
| ~~^~~
papricice.c: In function 'main':
papricice.c:68:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
68 | scanf("%d", &n);
| ^~~~~~~~~~~~~~~
papricice.c:72:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
72 | scanf("%d%d", &i, &j), i--, j--;
| ^~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
332 KB |
Output is correct |
| 2 |
Correct |
0 ms |
332 KB |
Output is correct |
| 3 |
Correct |
0 ms |
332 KB |
Output is correct |
| 4 |
Correct |
1 ms |
332 KB |
Output is correct |
| 5 |
Correct |
0 ms |
332 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
332 KB |
Output is correct |
| 2 |
Correct |
0 ms |
332 KB |
Output is correct |
| 3 |
Correct |
0 ms |
332 KB |
Output is correct |
| 4 |
Correct |
1 ms |
332 KB |
Output is correct |
| 5 |
Correct |
0 ms |
332 KB |
Output is correct |
| 6 |
Correct |
1 ms |
460 KB |
Output is correct |
| 7 |
Correct |
1 ms |
460 KB |
Output is correct |
| 8 |
Correct |
2 ms |
460 KB |
Output is correct |
| 9 |
Correct |
1 ms |
460 KB |
Output is correct |
| 10 |
Correct |
1 ms |
460 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
332 KB |
Output is correct |
| 2 |
Correct |
0 ms |
332 KB |
Output is correct |
| 3 |
Correct |
0 ms |
332 KB |
Output is correct |
| 4 |
Correct |
1 ms |
332 KB |
Output is correct |
| 5 |
Correct |
0 ms |
332 KB |
Output is correct |
| 6 |
Correct |
1 ms |
460 KB |
Output is correct |
| 7 |
Correct |
1 ms |
460 KB |
Output is correct |
| 8 |
Correct |
2 ms |
460 KB |
Output is correct |
| 9 |
Correct |
1 ms |
460 KB |
Output is correct |
| 10 |
Correct |
1 ms |
460 KB |
Output is correct |
| 11 |
Correct |
146 ms |
16620 KB |
Output is correct |
| 12 |
Correct |
152 ms |
16064 KB |
Output is correct |
| 13 |
Correct |
118 ms |
16836 KB |
Output is correct |
| 14 |
Correct |
156 ms |
16592 KB |
Output is correct |
| 15 |
Correct |
140 ms |
16184 KB |
Output is correct |
| 16 |
Correct |
97 ms |
16904 KB |
Output is correct |
| 17 |
Correct |
120 ms |
16312 KB |
Output is correct |
| 18 |
Correct |
130 ms |
20420 KB |
Output is correct |
| 19 |
Correct |
120 ms |
16636 KB |
Output is correct |
| 20 |
Correct |
119 ms |
16064 KB |
Output is correct |
