Submission #710425

#	Time	Username	Problem	Language	Result	Execution time	Memory
710425		hafo	Mecho (IOI09_mecho)	C++14	83 / 100	474 ms	6456 KiB

mecho

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define all(x) x.begin(), x.end()
using namespace std;

template<typename T1, typename T2> bool mini (T1 &a, T2 b) {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi (T1 &a, T2 b) {if(a < b) a = b; else return 0; return 1;}

const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 8e2 + 7;
const ll oo = 1e9 + 69;

int n, s, xd, yd, f[3][maxn][maxn];
char a[maxn][maxn];
pa d[] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};

void bfs(int t, int time) {
    memset(f[t], -1, sizeof f[t]);
    queue<pa> q;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < n; j++) {
            if(a[i][j] == 'M' && t != 0 && f[0][i][j] > time) {
                f[t][i][j] = 0;
                q.push({i, j});
            }
            if(a[i][j] == 'H' && t == 0) {
                f[t][i][j] = 0;
                q.push({i, j});
            }
        }

    while(!q.empty()) {
        int u = q.front().fi, v = q.front().se;
        q.pop();

        for(int k = 0; k < 4; k++) {
            int x = u + d[k].fi;
            int y = v + d[k].se;
            if(x < 0 || x == n || y < 0 || y == n || a[x][y] == 'T' || f[t][x][y] != -1 || a[x][y] == 'H') continue;
            if(t && f[0][x][y] != -1 && f[0][x][y] - (f[1][u][v] + 1) / s < time) continue;
            f[t][x][y] = f[t][u][v] + 1;
            q.push({x, y});
        }
    }
}

bool check(int time) {
    bfs(0, time);
    bfs(1, time);
    for(int k = 0; k < 4; k++) {
        int x = xd + d[k].fi;
        int y = yd + d[k].se;
        if(x < 0 || x == n || y < 0 || y == n || f[0][x][y] == -1 || f[1][x][y] == -1) continue;
        if(f[0][x][y] - f[1][x][y] / s > time) return 1;
    }
    return 0;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    //freopen(TASK".inp", "r", stdin);
    //freopen(TASK".out", "w", stdout);

    cin>>n>>s;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < n; j++){
            cin>>a[i][j];
            if(a[i][j] == 'D') {
                xd = i;
                yd = j;
            }
        }

    int l = 0, r = n * n, mid, res = -1;
    while(l <= r) {
        mid = l + r >> 1;
        if(check(mid)) {
            l = mid + 1;
            res = mid;
        } else r = mid -1 ;
    }
    cout<<res;
    return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:86:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   86 |         mid = l + r >> 1;
      |               ~~^~~

• Subtask 1: 83 / 100