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Submission #679603

# Submission time Handle Problem Language Result Execution time Memory
679603 2023-01-08T16:02:48 Z omikron123 Mecho (IOI09_mecho) C++14
100 / 100
 258 ms 7580 KB 
// https://oj.uz/problem/view/IOI09_mecho

#include <cstdio>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstring>
#include <queue>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;

// binary search + BFS

// n <= 800, s <= 1000
int n, s;
char m[805][805];
int mr,mc,dr,dc;
struct E {
    int r,c,d;
};
queue<E> q;
const int INF = 1e9;
int beetime[805][805];    // time for bees to reach here
int steps[805][805];    // min steps for mecho to reach here

// init q before calling this
void bfs() {
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            beetime[i][j] = -1;
    while (!q.empty()) {
        E e = q.front();
        q.pop();
        if (e.r < 0 || e.r >= n || e.c < 0 || e.c >= n) continue;
        if (m[e.r][e.c] == 'T' || m[e.r][e.c] == 'D' || beetime[e.r][e.c] != -1) continue;
        beetime[e.r][e.c] = e.d;
        q.push({e.r+1, e.c, e.d+1});
        q.push({e.r-1, e.c, e.d+1});
        q.push({e.r, e.c+1, e.d+1});
        q.push({e.r, e.c-1, e.d+1});
    }
}

// check if eating honey for t minutes is ok
bool check(int t) {
    q.push({mr, mc, t*s});
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            steps[i][j] = -1;
    while (!q.empty()) {
        E e = q.front();
        q.pop();
        if (e.r < 0 || e.r >= n || e.c < 0 || e.c >= n) continue;
        if (m[e.r][e.c] == 'T' || steps[e.r][e.c] != -1) continue;
        if (beetime[e.r][e.c] != -1 && e.d / s >= beetime[e.r][e.c]) continue; // stinged by bees
        steps[e.r][e.c] = e.d;
        q.push({e.r+1, e.c, e.d+1});
        q.push({e.r-1, e.c, e.d+1});
        q.push({e.r, e.c+1, e.d+1});
        q.push({e.r, e.c-1, e.d+1});
    }
    return steps[dr][dc] != -1;
}

int main() {
    scanf("%d %d", &n, &s);
    for (int i = 0; i < n; i++) {
        scanf("%s", m[i]);
        for (int j = 0; j < n; j++)
            if (m[i][j] == 'M') mr = i, mc = j;
            else if (m[i][j] == 'D') dr = i, dc = j;
            else if (m[i][j] == 'H') q.push({i,j,0});
    }

    bfs();      // calc beetime[][]

    int lo = 0, hi = 800*800;
    while (lo < hi) {
        int mid = (lo+hi+1) / 2;
        if (check(mid))
            lo = mid;
        else
            hi = mid-1;
    }
    if (lo == 0 && !check(0))
        printf("-1");
    else
        printf("%d", lo);

    return 0;
}

Compilation message

mecho.cpp: In function 'int main()':
mecho.cpp:67:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |     scanf("%d %d", &n, &s);
      |     ~~~~~^~~~~~~~~~~~~~~~~
mecho.cpp:69:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |         scanf("%s", m[i]);
      |         ~~~~~^~~~~~~~~~~~

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 0 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 168 ms 6584 KB Output is correct
8 Correct 0 ms 340 KB Output is correct
9 Correct 0 ms 340 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 1 ms 724 KB Output is correct
13 Correct 1 ms 596 KB Output is correct
14 Correct 1 ms 724 KB Output is correct
15 Correct 0 ms 340 KB Output is correct
16 Correct 0 ms 340 KB Output is correct
17 Correct 0 ms 468 KB Output is correct
18 Correct 0 ms 468 KB Output is correct
19 Correct 0 ms 480 KB Output is correct
20 Correct 0 ms 468 KB Output is correct
21 Correct 1 ms 468 KB Output is correct
22 Correct 1 ms 468 KB Output is correct
23 Correct 1 ms 596 KB Output is correct
24 Correct 1 ms 596 KB Output is correct
25 Correct 1 ms 724 KB Output is correct
26 Correct 1 ms 724 KB Output is correct
27 Correct 1 ms 724 KB Output is correct
28 Correct 1 ms 724 KB Output is correct
29 Correct 1 ms 724 KB Output is correct
30 Correct 1 ms 724 KB Output is correct
31 Correct 1 ms 724 KB Output is correct
32 Correct 1 ms 724 KB Output is correct
33 Correct 5 ms 2772 KB Output is correct
34 Correct 6 ms 2704 KB Output is correct
35 Correct 36 ms 2772 KB Output is correct
36 Correct 7 ms 3028 KB Output is correct
37 Correct 9 ms 3028 KB Output is correct
38 Correct 53 ms 3156 KB Output is correct
39 Correct 8 ms 3412 KB Output is correct
40 Correct 10 ms 3428 KB Output is correct
41 Correct 56 ms 3492 KB Output is correct
42 Correct 10 ms 3796 KB Output is correct
43 Correct 10 ms 3796 KB Output is correct
44 Correct 76 ms 3852 KB Output is correct
45 Correct 13 ms 4180 KB Output is correct
46 Correct 17 ms 4128 KB Output is correct
47 Correct 87 ms 4212 KB Output is correct
48 Correct 13 ms 4460 KB Output is correct
49 Correct 15 ms 4444 KB Output is correct
50 Correct 98 ms 4564 KB Output is correct
51 Correct 17 ms 4912 KB Output is correct
52 Correct 19 ms 4904 KB Output is correct
53 Correct 145 ms 4820 KB Output is correct
54 Correct 22 ms 5236 KB Output is correct
55 Correct 20 ms 5260 KB Output is correct
56 Correct 155 ms 5288 KB Output is correct
57 Correct 24 ms 5560 KB Output is correct
58 Correct 26 ms 5556 KB Output is correct
59 Correct 163 ms 5596 KB Output is correct
60 Correct 29 ms 5952 KB Output is correct
61 Correct 34 ms 5884 KB Output is correct
62 Correct 213 ms 6000 KB Output is correct
63 Correct 184 ms 5888 KB Output is correct
64 Correct 258 ms 5972 KB Output is correct
65 Correct 201 ms 5964 KB Output is correct
66 Correct 158 ms 5972 KB Output is correct
67 Correct 159 ms 5960 KB Output is correct
68 Correct 71 ms 6132 KB Output is correct
69 Correct 52 ms 6092 KB Output is correct
70 Correct 51 ms 6092 KB Output is correct
71 Correct 48 ms 6060 KB Output is correct
72 Correct 38 ms 6064 KB Output is correct
73 Correct 53 ms 7512 KB Output is correct
74 Correct 83 ms 7500 KB Output is correct
75 Correct 117 ms 7532 KB Output is correct
76 Correct 110 ms 7580 KB Output is correct
77 Correct 104 ms 7508 KB Output is correct
78 Correct 136 ms 7360 KB Output is correct
79 Correct 71 ms 7368 KB Output is correct
80 Correct 94 ms 7436 KB Output is correct
81 Correct 106 ms 7428 KB Output is correct
82 Correct 87 ms 7436 KB Output is correct
83 Correct 129 ms 7112 KB Output is correct
84 Correct 108 ms 7088 KB Output is correct
85 Correct 113 ms 7116 KB Output is correct
86 Correct 131 ms 6992 KB Output is correct
87 Correct 109 ms 7140 KB Output is correct
88 Correct 141 ms 6836 KB Output is correct
89 Correct 134 ms 6860 KB Output is correct
90 Correct 137 ms 6892 KB Output is correct
91 Correct 131 ms 6844 KB Output is correct
92 Correct 125 ms 6860 KB Output is correct