Submission #972934

#	Time	Username	Problem	Language	Result	Execution time	Memory
972934		jadai007	Mecho (IOI09_mecho)	C++17	18 / 100	261 ms	65536 KiB

mecho

#include<bits/stdc++.h>
 
using namespace std;
 
int n,s, bee[808][808], xx[] = {0, 0, -1, 1}, xy[] = {-1, 1, 0, 0}, bear[808][808], ans;
char mp[808][808];
pair<int, int> start, en;
queue<tuple<int, int, int>> q;
 
bool solve(int mid){
    for(int i = 1; i<=n; ++i) for(int j = 1; j<=n; ++j) bear[i][j] = 1e9;
    bear[start.first][start.second] = mid*s;
    q.emplace(start.first, start.second, mid*s);
    while(!q.empty()){
        int x = get<0>(q.front()), y = get<1>(q.front()), w = get<2>(q.front()); q.pop();
        if(x == en.first && y == en.second) return true;
        if (w%s == 0) if((w+s-1)/s >= bee[x][y]) continue;
        else if((w+s-1)/s > bee[x][y]) continue;
        bear[x][y] = w;
        for(int i = 0; i<4; ++i){
            int nx = x + xx[i];
            int ny = y + xy[i];
            if(nx < 1 || ny < 1 || nx > n || ny > n || mp[nx][ny] == 'T' || mp[nx][ny] == 'H') continue;
            if(bear[nx][ny] > w + 1) q.emplace(nx, ny, w + 1);
        }
    }
    return false;
}
 
int main(){
    cin.tie(nullptr)->sync_with_stdio(false);
    cin >> n >> s;
    for(int i = 1; i<=n; ++i){
        for(int j = 1; j<=n; ++j){
            cin >> mp[i][j];
            if(mp[i][j] == 'M') start = {i, j};
            else if(mp[i][j] == 'D') en = {i, j};
        }
    }
    for(int i = 1; i<=n; ++i) for(int j = 1; j<=n; ++j) bee[i][j] = 1e9;
    for(int i = 1; i<=n; ++i){
        for(int j = 1; j<=n; ++j){
            if(mp[i][j] == 'H'){
                bee[i][j] = 0;
                q.emplace(i, j, 0);
            }
        }
    }
    while(!q.empty()){
        int x = get<0>(q.front()), y = get<1>(q.front()), w = get<2>(q.front());
        q.pop();
        for(int i = 0; i<4; ++i){
            int nx = x + xx[i];
            int ny = y + xy[i];
            if(nx < 1 || n < 1 || nx > n || ny > n || mp[nx][ny] == 'T') continue;
            if(bee[nx][ny] > w + 1){
                bee[nx][ny] = w + 1;
                q.emplace(nx, ny, w + 1);
            }
        }
    }
    int l = 1, r = 1e9;
    while(l <= r){
        int mid = (l + r) >> 1;
        while(!q.empty()) q.pop();
        if(solve(mid)){
            ans = mid;
            l = mid + 1;
        }
        else r = mid - 1;
    }
    cout << ans;
}

Compilation message (stderr)

mecho.cpp: In function 'bool solve(int)':
mecho.cpp:17:12: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   17 |         if (w%s == 0) if((w+s-1)/s >= bee[x][y]) continue;
      |            ^

• Subtask 1: 18 / 100