Submission #1105469

#	Time	Username	Problem	Language	Result	Execution time	Memory
1105469		Zone_zonee	Mecho (IOI09_mecho)	C++17	100 / 100	129 ms	6480 KiB

mecho

#include <bits/stdc++.h>
using namespace std;

int n, s;
char inp[808][808];
int bee[808][808];
int dis[808][808];
const int dr[] = {1, -1, 0, 0}, dc[] = {0, 0, 1, -1};
pair<int, int> st;
bool solve(int mid){
    queue<tuple<int, int, int>> q;
    q.emplace(st.first, st.second, 0);
    for(int i = 1; i <= n; ++i) for(int j = 1; j <= n; ++j) dis[i][j] = (inp[i][j] == 'M' ? 0 : 1e9);
    while(!q.empty()){
        auto [x, y, d1] = q.front(); q.pop();
        if(dis[x][y] < d1 || (dis[x][y] / s >= bee[x][y] - mid && bee[x][y] != -1)) continue;
        if(inp[x][y] == 'D') return true;
        for(int i = 0; i < 4; ++i){
            int nx = x+dr[i];
            int ny = y+dc[i];
            if(nx <= 0 || nx > n || ny <= 0 || ny > n) continue;
            if(inp[nx][ny] != 'T' && dis[nx][ny] > d1 + 1){
                q.emplace(nx, ny, dis[nx][ny] = d1+1);
            }
        }
    }
    return false;
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    queue<pair<int, int>> q;
    cin >> n >> s;
    memset(bee, -1, sizeof bee);
    for(int i = 1; i <= n; ++i) for(int j = 1; j <= n; ++j){
        cin >> inp[i][j];
        if(inp[i][j] == 'M') st = {i, j};
        else if(inp[i][j] == 'H'){
            q.emplace(i, j);
            bee[i][j] = 0;
        }
    }
    while(!q.empty()){
        auto [x, y] = q.front(); q.pop();
        for(int i = 0; i < 4; ++i){
            int nx = x+dr[i];
            int ny = y+dc[i];
            if(nx <= 0 || nx > n || ny <= 0 || ny > n) continue;
            if(inp[nx][ny] == 'D' || inp[nx][ny] == 'T' || bee[nx][ny] != -1) continue;
            bee[nx][ny] = bee[x][y] + 1;
            q.emplace(nx, ny);
        }
    }
    int l = 0, r = 1e6, ans = -1;
    while(l <= r){
        int mid = (l+r)>>1;
        if(solve(mid)) ans = mid, l = mid+1;
        else r = mid-1;
    }
    cout << ans;
}

• Subtask 1: 100 / 100