Submission #93830

#	Time	Username	Problem	Language	Result	Execution time	Memory
93830		dalgerok	Bomb (IZhO17_bomb)	C++14	100 / 100	465 ms	61688 KiB

bomb

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



const int N = 2505, INF = 2e9;



int n, m, dn[N][N], up[N][N];
char a[N][N];
int dp[N];


int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            cin >> a[i][j];
        }
    }
    int mnw = INF, mnh = INF;
    for(int i = 1; i <= n; i++){
        int cur = 0;
        for(int j = 1; j <= m; j++){
            if(a[i][j] == '1'){
                cur += 1;
            }
            else if(cur > 0){
                mnw = min(mnw, cur);
                cur = 0;
            }
        }
        if(cur > 0){
            mnw = min(mnw, cur);
        }
    }
    for(int j = 1; j <= m; j++){
        int cur = 0;
        for(int i = 1; i <= n; i++){
            if(a[i][j] == '1'){
                cur += 1;
            }
            else if(cur > 0){
                mnh = min(mnh, cur);
                cur = 0;
            }
        }
        if(cur > 0){
            mnh = min(mnh, cur);
        }
    }
    for(int j = 1; j <= m; j++){
        for(int i = 1; i <= n; i++){
            if(a[i][j] == '1'){
                up[i][j] = up[i - 1][j] + 1;
            }
        }
        for(int i = n; i >= 1; i--){
            if(a[i][j] == '1'){
                dn[i][j] = dn[i + 1][j] + 1;
            }
        }
    }
    for(int i = 1; i <= mnw; i++){
        dp[i] = mnh;
    }
    for(int i = 1; i <= n; i++){
        int l = INF, r = INF, cur = 0;
        for(int j = 1; j <= m; j++){
            if(a[i][j] == '1'){
                l = min(l, up[i][j]);
                r = min(r, dn[i][j]);
                cur += 1;
                dp[cur] = min(dp[cur], l + r - 1);
            }
            else{
                l = r = INF;
                cur = 0;
            }
        }
        l = r = INF;
        cur = 0;
        for(int j = m; j >= 1; j--){
            if(a[i][j] == '1'){
                l = min(l, up[i][j]);
                r = min(r, dn[i][j]);
                cur += 1;
                dp[cur] = min(dp[cur], l + r - 1);
            }
            else{
                l = r = INF;
                cur = 0;
            }
        }
    }
    int ans = dp[1];
    for(int i = 2; i <= mnw; i++){
        dp[i] = min(dp[i], dp[i - 1]);
        ans = max(ans, dp[i] * i);
    }
    cout << ans;
}

• Subtask 1: 100 / 100