Submission #718787

#	Time	Username	Problem	Language	Result	Execution time	Memory
718787		NintsiChkhaidze	Mecho (IOI09_mecho)	C++17	30 / 100	144 ms	65536 KiB

mecho

#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define f first
#define s second
#define int ll
using namespace std;

const int inf = 1e18,N = 805;

char a[N][N];
int dis[N][N],xm,ym,n,S;
bool fix[N][N];
vector <pair<int,int> > neighbours = {{0,1}, {0,-1},{1,0}, {-1,0}}; 

bool check(int t){
    if (dis[xm][ym] <= t*S) return 0;
    for (int i=1;i<=n;i++)
        for (int j=1;j<=n;j++)
            fix[i][j]=0;

    queue <pair <int,pair<int,int> > > q;
    while (q.size()) q.pop();
    q.push({t*S,{xm,ym}});
    fix[xm][ym] = 1;
    while (q.size()){
        int T = q.front().f,x = q.front().s.f,y = q.front().s.s;
        q.pop();
        if (a[x][y] == 'D') return 1;

        for (auto [dx,dy]: neighbours){
            int X = x+dx,Y = y+dy;
            if (X < 1 || Y < 1 || X > n || Y > n || fix[X][Y]) continue;
            if (a[X][Y] == 'T' || a[X][Y] == 'H') continue;
            if (dis[X][Y] <= T + 1) continue;
            q.push({T+1,{X,Y}});
        }
    }   
    return 0;
}
signed main() {
    ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
    	
    cin>>n>>S;
    queue <pair<int,pair<int,int> > > q;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++){
            cin >> a[i][j];
            dis[i][j] = inf;
            if (a[i][j] == 'H') dis[i][j] = 0,q.push({0,{i,j}}),fix[i][j] = 1;
            if (a[i][j] == 'M') xm = i,ym = j;
        }
        
    while (q.size()){
        int d = q.front().f,x = q.front().s.f,y = q.front().s.s;
        q.pop();
        for (auto [dx,dy]: neighbours){
            int X = x+dx,Y = y+dy;
            if (X < 1 || Y < 1 || X > n || Y > n) continue;
            if (fix[X][Y] || (a[X][Y] == 'T' || a[X][Y] == 'D')) continue;
            dis[X][Y] = d + S;
            fix[X][Y] = 1;
            q.push({d+S,{X,Y}});
        }
    }

    int l = 0,r = 1e9,ans=-1;
    while (l <= r){
        int mid = (l + r)>>1;
        if (check(mid)) {
            ans = mid,l = mid + 1;
        }else{
            r = mid - 1;
        }
    }
    cout<<ans;
}

• Subtask 1: 30 / 100