Bomb

input/code.cpp: In function 'int main()':
input/code.cpp:101:19: warning: operation on 'idx' may be undefined [-Wsequence-point]
         mx_height[++idx] = min(mx_height[idx], u+d-1);
                   ^~~~~
input/code.cpp:114:19: warning: operation on 'idx' may be undefined [-Wsequence-point]
         mx_height[++idx] = min(mx_height[idx], u+d-1);
                   ^~~~~

#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define IO ios_base::sync_with_stdio(0); cin.tie(0)
#define F first
#define S second
#define pb push_back
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define N 2505
bool A[N][N];
int dp[N][N];
int up[N][N], down[N][N];
int mx_height[N];

int n, m;

int scanline(int y) {
  // Scan minimum constraint for width.
  int mn = 1e9;
  int c = 0;
  FOR(x,1,m+1) {
    if (A[y][x]) {
      c++;
    } else {
      if (c == 0) continue;
      mn = min(mn, c);
      c = 0;
    }
  }

  if (c != 0) mn = min(c, mn);

  return mn;
}

int scancol(int x) {
  // Scan minimum constraint for height.
  int mn = 1e9;
  int c = 0;
  FOR(y,1,n+1) {
    if (A[y][x]) {
      c++;
    } else {
      if (c == 0) continue;
      mn = min(mn, c);
      c = 0;
    }
  }

  if (c != 0) mn = min(c, mn);

  return mn;
}



int main() {
  IO; cin>>n>>m;
  FOR(y,1,n+1) {
    FOR(x,1,m+1) {
      char c; cin>>c;
      if (c == '1') A[y][x] = true;
    }
  }

  int H = n, W = m;
  FOR(y,1,n+1) {
    int r = scanline(y);
    if (r == 1e9) continue;
    W = min(W, r);
  }

  FOR(x,1,m+1) {
    int r = scancol(x);
    if (r == 1e9) continue;
    H = min(H, r);
  }

  FOR(x,1,m+1) {
    for (int y = n; y >= 1; y--) {
      if (A[y][x]) down[y][x] = down[y+1][x] + 1;
    }

    FOR(y,1,n+1) {
      if (A[y][x]) up[y][x] = up[y-1][x] + 1;
    }
  }

  FOR(w,1,W+1) mx_height[w] = H;
  FOR(y,1,n+1) {
    int idx = 0, u = 1e9, d = 1e9;

    FOR(x,1,m+1) {
      if (A[y][x]) {
        // Increase width
        u = min(u, up[y][x]);
        d = min(d, down[y][x]);
        mx_height[++idx] = min(mx_height[idx], u+d-1);
      } else {
        u = d = 1e9;
        idx = 0;
      }
    }

    d = u = 1e9; idx = 0;
    for (int x = m; x >= 1; x--) {
      if (A[y][x]) {
        // Increase width
        u = min(u, up[y][x]);
        d = min(d, down[y][x]);
        mx_height[++idx] = min(mx_height[idx], u+d-1);
      } else {
        u = d = 1e9;
        idx = 0;
      }
    }
  }

  int ans = 0;
  int cr = mx_height[1];
  FOR(w,1,W+1) {
    cr = min(cr, mx_height[w]);
    ans = max(ans, w * cr);
  }

  cout<<ans<<"\n";
}

Test 1

Group: 1

Verdict: WRONG ANSWER

Test 2

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Verdict: WRONG ANSWER

Test 3

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Test 4

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Test 6

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Test 8

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Test 9

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Test 10

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Test 11

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Test 12

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Test 15

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Test 18

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Test 21

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Test 30

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Test 45

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Test 48

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Test 49

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Test 50

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Test 59

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Test 60

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Test 61

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Test 62

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Test 63

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Test 64

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Test 65

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Test 66

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Test 67

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Test 68

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Test 69

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Test 70

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Test 71

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Test 72

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Test 73

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Test 74

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Test 75

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Test 76

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Test 77

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Test 78

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Test 79

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Test 80

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Test 81

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Test 82

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Test 83

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Test 84

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Test 85

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Test 86

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Test 87

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Test 88

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Test 89

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Test 90

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Test 91

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Test 92

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Test 93

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Test 94

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Test 95

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Test 96

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Test 97

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Test 98

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Test 99

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Test 100

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Verdict: WRONG ANSWER