CODE EXAMPLE FOR PYTHON

Prefix Sum of Matrix (Or 2D Array)

<script>
// Javascript program to find prefix sum of 2D array
 
// calculating new array
function prefixSum2D(a)
{
    let R = a.length;
        let C = a[0].length;
  
        let psa = new Array(R);
        for(let i = 0; i < R; i++)
        {
            psa[i] = new Array(C);
            for(let j = 0; j < C; j++)
                psa[i][j] = 0;
        }   
  
        psa[0][0] = a[0][0];
  
        // Filling first row and first column
        for (let i = 1; i < C; i++)
            psa[0][i] = psa[0][i - 1] + a[0][i];
        for (let i = 1; i < R; i++)
            psa[i][0] = psa[i - 1][0] + a[i][0];
  
        // updating the values in the
        // cells as per the general formula.
        for (let i = 1; i < R; i++)
            for (let j = 1; j < C; j++)
  
                // values in the cells of new array
                // are updated
                psa[i][j] = psa[i - 1][j] + psa[i][j - 1]
                            - psa[i - 1][j - 1] + a[i][j];
  
        for (let i = 0; i < R; i++) {
            for (let j = 0; j < C; j++)
                document.write(psa[i][j] + " ");
            document.write("<br>");
        }
}
 
// driver code
let a=[[ 1, 1, 1, 1, 1 ],
                      [ 1, 1, 1, 1, 1 ],
                      [ 1, 1, 1, 1, 1 ],
                      [ 1, 1, 1, 1, 1 ]];
prefixSum2D(a);
 
// This code is contributed by avanitrachhadiya2155
</script>