Cracking the Coding Interview, 4 Edition - 150 Programming Interview Questions and Solutions

Solutions to Chapter 20 | Hard
32 matrix[i][j];
33 }
34 }
35 }
36 return sumMatrix;
37 }
38
39 private static int computeSum(int[][] sumMatrix, int i1, int i2,
40 int j1, int j2) {
41 if (i1 == 0 && j1 == 0) { // starts at row 0, column 0
42 return sumMatrix[i2][j2];
43 } else if (i1 == 0) { // start at row 0
44 return sumMatrix[i2][j2] - sumMatrix[i2][j1 - 1];
45 } else if (j1 == 0) { // start at column 0
46 return sumMatrix[i2][j2] - sumMatrix[i1 - 1][j2];
47 } else {
48 return sumMatrix[i2][j2] - sumMatrix[i2][j1 - 1]
49 - sumMatrix[i1 - 1][j2] + sumMatrix[i1 - 1][j1 - 1];
50 }
51 }
2 9 7
Cracking the Coding Interview | Additional Review Problems