Submission #96765

#	Time	Username	Problem	Language	Result	Execution time	Memory
96765		choikiwon	Bomb (IZhO17_bomb)	C++17	99 / 100	921 ms	107896 KiB

bomb

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

typedef pair<int, int> pii;

const int MN = 2525;

int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};

int N, M;
char G[MN][MN];

int cc[MN][MN][4];
int dp(int r, int c, int d) {
    if(r < 0 || N <= r || c < 0 || M <= c) return 0;
    int &ret = cc[r][c][d];
    if(ret != -1) return ret;
    if(G[r][c] == '0') return ret = 0;
    return ret = dp(r + dy[d], c + dx[d], d) + 1;
}

int mn[MN];

int main() {
    //freopen("input.txt", "r", stdin);

    scanf("%d %d", &N, &M);

    for(int i = 0; i < N; i++) {
        scanf("\n");
        for(int j = 0; j < M; j++) {
            scanf("%c", &G[i][j]);
        }
    }
    //*/
    memset(cc, -1, sizeof(cc));

    int mnh = 1e9;
    int mnw = 1e9;
    for(int i = 0; i < N; i++) for(int j = 0; j < M; j++) if(G[i][j] == '1') {
        mnh = min(mnh, dp(i, j, 0) + dp(i, j, 1) - 1);
        mnw = min(mnw, dp(i, j, 2) + dp(i, j, 3) - 1);
    }

    for(int i = 0; i <= mnw; i++) mn[i] = 1e9;
    mn[0] = mnh;
    for(int i = 0; i < N; i++) {
        int len = 0;
        int chk1 = 0, chk2 = 0;
        for(int j = 0; j < M; j++) {
            if(G[i][j] == '1') {
                if(dp(i, j, 3) == 1) {
                    len = 1;
                }
                if(len) {
                    if(dp(i, j, 0) == 1) chk1 = 1;
                    if(chk1) mn[len] = min(mn[len], dp(i, j, 1));
                    if(dp(i, j, 1) == 1) chk2 = 1;
                    if(chk2) mn[len] = min(mn[len], dp(i, j, 0));
                }
                len++;
            }
            else len = 0, chk1 = 0, chk2 = 0;
        }
        len = 0;
        chk1 = 0, chk2 = 0;
        for(int j = M - 1; j >= 0; j--) {
            if(G[i][j] == '1') {
                if(dp(i, j, 2) == 1) {
                    len = 1;
                }
                if(len) {
                    if(dp(i, j, 0) == 1) chk1 = 1;
                    if(chk1) mn[len] = min(mn[len], dp(i, j, 1));
                    if(dp(i, j, 1) == 1) chk2 = 1;
                    if(chk2) mn[len] = min(mn[len], dp(i, j, 0));
                }
                len++;
            }
            else len = 0, chk1 = 0, chk2 = 0;
        }
    }
    /*
    for(int i = 0; i < N; i++) {
        int tmn = 1e9;
        int len = 0;
        for(int j = 0; j < M; j++) {
            if(G[i][j] == '1') {
                if(len) tmn = min(tmn, dp(i, j, 1));
                if(dp(i, j, 0) == 1) {
                    if(len) mn[len - 1] = min(mn[len - 1], tmn);
                    tmn = dp(i, j, 1);
                    len = 1;
                }
                if(len) len++;
            }
            else tmn = 1e9, len = 0;
        }
        tmn = 1e9;
        len = 0;
        for(int j = 0; j < M; j++) {
            if(G[i][j] == '1') {
                if(len) tmn = min(tmn, dp(i, j, 0));
                if(dp(i, j, 1) == 1) {
                    if(len) mn[len - 1] = min(mn[len - 1], tmn);
                    tmn = dp(i, j, 0);
                    len = 1;
                }
                if(len) len++;
            }
            else tmn = 1e9, len = 0;
        }
    }
    //*/

    int ans = 0;
    for(int i = 1; i <= mnw; i++) {
        mn[i] = min(mn[i], mn[i - 1]);
        ans = max(ans, mn[i] * i);
    }
    printf("%d", ans);
}

Compilation message (stderr)

bomb.cpp: In function 'int main()':
bomb.cpp:28:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &N, &M);
     ~~~~~^~~~~~~~~~~~~~~~~
bomb.cpp:31:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("\n");
         ~~~~~^~~~~~
bomb.cpp:33:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%c", &G[i][j]);
             ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 99 / 100