51Nod-1157-全是1的最大子矩阵

描述

题解

代码

#include <iostream>

using namespace std;

const int N = 105;

int m, n;
bool a

;

int Run(const int &m, const int &n)     // a[1...m][1...n]
{                                       // O(m*n)
int i, j, k, l, r, max = 0;
int col
;
for (j = 1; j <= n; j++)
{
if (a[1][j] == 0 )
{
col[j] = 0;
}
else
{
for (k = 2; k <= m && a[k][j] == 1; k++);
col[j] = k - 1;
}
}
for (i = 1; i <= m; i++)
{
if (i > 1)
{
for (j = 1; j <= n; j++)
{
if (a[i][j] == 0)
{
col[j] = 0;
}
else
{
if (a[i - 1][j] == 0)
{
for (k = i + 1; k <= m && a[k][j] == 1; k++);
col[j] = k-1;
}
}
}
}
for (j = 1; j <= n; j++)
{
if (col[j] >= i)
{
for (l = j - 1; l > 0 && col[l] >= col[j]; --l);
l++;
for (r = j + 1; r <= n && col[r] >= col[j]; ++r);
r--;
int res = (r - l + 1) * (col[j] - i + 1);
if( res > max )
{
max = res;
}
}
}
}

return max;
}

int main()
{
cin >> m >> n;

for (int i = 1; i <= m; i++)
{
for (int j = 1; j <= n; j++)
{
cin >> a[i][j];
}
}

cout << Run(m, n) << '\n';

return 0;
}

参考