#include<bits/stdc++.h> using namespace std; const int N = 2550; int ans; int x[N]; int n, m, a[N][N]; int s[N][N], H, W; int f[N][N], bad[N][N]; int dpw[N], dph[N]; char S[N]; inline void press(int i, int j, int h, int w) { bad[i][j]++; bad[i + h][j + w]++; bad[i + h][j]--; bad[i][j + w]--; } inline bool can(int h, int w) { for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j) bad[i][j] = 0, f[i][j] = 0; for(int i = 1; i + h - 1 <= n; ++i) for(int j = 1; j + w - 1 <= m; ++j) if(s[i + h - 1][j + w - 1] - s[i + h - 1][j - 1] - s[i - 1][j + w - 1] + s[i - 1][j - 1] == h * w) press(i, j, h, w); for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j) { f[i][j] = f[i - 1][j] + f[i][j - 1] - f[i - 1][j - 1] + bad[i][j]; if(a[i][j] == 1 && f[i][j] <= 0) return false; } return true; } inline int getw(int h) { if(dpw[h] != -1) return dpw[h]; int L = 0, R = W + 1; while(L + 1 < R) { int w = (L + R) >> 1; if(can(h, w)) L = w; else R = w; } return dpw[h] = L; } inline int geth(int w) { if(dph[w] != -1) return dph[w]; int L = 0, R = H + 1; while(L + 1 < R) { int h = (L + R) >> 1; if(can(h, w)) L = h; else R = h; } return dph[w] = L; } int main() { scanf("%d%d", &n, &m); for(int i = 0; i < 2550; ++i) dpw[i] = dph[i] = -1; for(int i = 2; i <= n + 1; ++i) { scanf("%s\n", S); for(int j = 2; j <= m + 1; ++j) a[i][j] = S[j - 2] - '0'; } n += 2, m += 2; for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j) s[i][j] = s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1] + a[i][j]; H = n, W = m; for(int i = 1; i <= n; ++i) { int cnt = 0; for(int j = 1; j <= m; ++j) if(a[i][j] == 1) cnt++; else { if(cnt) W = min(W, cnt); cnt = 0; } } for(int j = 1; j <= m; ++j) { int cnt = 0; for(int i = 1; i <= n; ++i) if(a[i][j] == 1) cnt++; else { if(cnt) H = min(H, cnt); cnt = 0; } } for(int i = 1; i <= H;i++) { int x = getw(i); //int y = geth(x); ans = max(ans, i * x); //i = y + 1; } ans = max(ans, max(W, H)); printf("%d\n", ans); return 0; }

bomb.cpp: In function 'int main()':
bomb.cpp:75:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         scanf("%d%d", &n, &m);
      |         ~~~~~^~~~~~~~~~~~~~~~
bomb.cpp:81:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |                 scanf("%s\n", S);
      |                 ~~~~~^~~~~~~~~~~