Submission #245582

#	Time	Username	Problem	Language	Result	Execution time	Memory
245582		tatyam	Mecho (IOI09_mecho)	C++17	100 / 100	272 ms	6336 KiB

mecho

#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int INF = 0x3fffffff;
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
#define name2(a,b,c,...) c
#define rep1(b) for(int i = 0; i < b; i++)
#define rep2(i,b) for(int i = 0; i < b; i++)
#define rep(...) name2(__VA_ARGS__,rep2,rep1)(__VA_ARGS__)
#define each(i,a) for(auto&& i : a)
template<class T, class U> bool chmin(T& a, const U& b){ if(a > b){ a = b; return 1; } return 0; }
template<class T, class U> bool chmax(T& a, const U& b){ if(a < b){ a = b; return 1; } return 0; }
 
 
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n, s;
    cin >> n >> s;
    vector<string> a(n);
    each(i, a) cin >> i;
    vector<vector<int>> bee(n, vector<int>(n, INF));
    queue<pii> q;
    rep(n) rep(j, n) if(a[i][j] == 'H'){
        bee[i][j] = 0;
        q.emplace(i, j);
    }
    while(q.size()){
        auto [x, y] = q.front();
        q.pop();
        rep(4){
            int x2 = x + dx[i], y2 = y + dy[i];
            if(x2 < 0 || y2 < 0 || x2 >= n || y2 >= n || a[x2][y2] != 'G' && a[x2][y2] != 'M') continue;
            if(chmin(bee[x2][y2], bee[x][y] + 1)) q.emplace(x2, y2);
        }
    }
    pii start, goal;
    rep(n) rep(j, n) if(a[i][j] == 'M') start = {i, j};
    rep(n) rep(j, n) if(a[i][j] == 'D') goal = {i, j};
    auto check = [&](int v) -> bool {
        if(bee[start.first][start.second] <= v) return false;
        vector<vector<int>> m(n, vector<int>(n, INF));
        m[start.first][start.second] = 0;
        q.push(start);
        while(q.size()){
            auto [x, y] = q.front();
            q.pop();
            int next = m[x][y] + 1;
            rep(4){
                int x2 = x + dx[i], y2 = y + dy[i];
                if(x2 < 0 || y2 < 0 || x2 >= n || y2 >= n || a[x2][y2] == 'T') continue;
                if(next / s + v < bee[x2][y2] && chmin(m[x2][y2], next)) q.emplace(x2, y2);
            }
        }
        return m[goal.first][goal.second] != INF;
    };
    int ok = -1, ng = n * n;
    while(ng - ok > 1){
        int cen = (ok + ng) / 2;
        if(check(cen)) ok = cen;
        else ng = cen;
    }
    cout << ok << endl;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:34:75: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
             if(x2 < 0 || y2 < 0 || x2 >= n || y2 >= n || a[x2][y2] != 'G' && a[x2][y2] != 'M') continue;

• Subtask 1: 100 / 100