Given a binary matrix, find out the maximum size square sub-matrix with all 1s.
For example, consider the below binary matrix.0 1 1 0 1 1 1 0 1 0 0 1 1 1 0 1 1 1 1 0 1 1 1 1 1 0 0 0 0 0The maximum square sub-matrix with all set bits is
1 1 1
1 1 1
1 1 1
http://www.geeksforgeeks.org/maximum-size-sub-matrix-with-all-1s-in-a-binary-matrix/
Method 1:Dynamic Programming
#include<stdio.h>
#define bool int
#define R 6
#define C 5
int min(int a, int b, int c)
{
int m = a;
if (m > b)
m = b;
if (m > c)
m = c;
return m;
}
void printMaxSubSquare(bool M[R][C])
{
int i,j;
int S[R][C];
int max_of_s, max_i, max_j;
for(i = 0; i < R; i++)
S[i][0] = M[i][0];
for(j = 0; j < C; j++)
S[0][j] = M[0][j];
for(i = 1; i < R; i++)
{
for(j = 1; j < C; j++)
{
if(M[i][j] == 1)
S[i][j] = min(S[i][j-1], S[i-1][j], S[i-1][j-1]) + 1;
else
S[i][j] = 0;
}
}
max_of_s = S[0][0]; max_i = 0; max_j = 0;
for(i = 0; i < R; i++)
{
for(j = 0; j < C; j++)
{
if(max_of_s < S[i][j])
{
max_of_s = S[i][j];
max_i = i;
max_j = j;
}
}
}
printf("\nMaximum size sub-matrix is: \n");
for(i = max_i; i > max_i - max_of_s; i--)
{
for(j = max_j; j > max_j - max_of_s; j--)
{
printf("%d ", M[i][j]);
}
printf("\n");
}
}
int main()
{
bool M[R][C] = {{0, 1, 1, 0, 1},
{1, 1, 0, 1, 0},
{0, 1, 1, 1, 0},
{1, 1, 1, 1, 0},
{1, 1, 1, 1, 1},
{0, 0, 0, 0, 0}};
printMaxSubSquare(M);
getchar();
}
Time Complexity: O(m*n) where m is number of rows and n is number of columns in
the given matrix.
Auxiliary Space: O(m*n) where m is number of rows and n is number of columns in
the given matrix.
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