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Binary Matrix

For a binary matrix of size n x m of 0's and 1's. eg
1 0 0 1
0 0 1 0
0 0 0 0

If a location has 1; make all the elements of that row and column = 1. eg
1 1 1 1
1 1 1 1
1 0 1 1

Solution should be with Time complexity = O(n*m) and space complexity = O(1)

Will post answer in comments. Try till then.
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  1. AshuDecember 24, 2009 at 3:53 AM

    Take two variable
    row0 = 0
    col0 = 0
    row0 += for (i=0 to n) arr[0][i]
    col0 += for (i=0 to m) arr[i][0]
    for ( i=0;i<n;i++)
    for ( j=0;j<m;j++)
    {
    if ( arr[i][j])
    {
    arr[0][j] =1;
    arr[i][0] =1;
    break;
    }
    }

    for ( i=1;i<n;i++)
    {
    if( arr[i][0])
    for( j=1;j<m;j++)
    arr[i][j] =1;
    }
    for ( j=1;j<m;j++)
    {
    if ( arr[0][j])
    for( j=1;j<m;j++)
    arr[i][j] =1;

    }
    if (row0) for(j=0;j<m;j++) arr[0][j] = 1;
    if (col0) for(i=0;i<n;i++) arr[i][0] = 1;

    ReplyDelete

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