Question Definition
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
Follow up: Did you use extra space? A straight forward solution using O(mn) space is probably a bad idea. A simple improvement uses O(m + n) space, but still not the best solution. Could you devise a constant space solution?
Java Solution
public void setZeroes(int[][] matrix) {
boolean iZero = false;
for(int i = 0; i < matrix.length; i++){
if(matrix[i][0] == 0){
iZero = true;
break;
}
}
boolean jZero = false;
for(int j = 0; j < matrix[0].length; j++){
if(matrix[0][j] == 0){
jZero = true;
break;
}
}
for(int i = 1; i < matrix.length; i++){
for(int j = 1; j < matrix[i].length; j++){
if(matrix[i][j] == 0){
matrix[i][0] = 0;
matrix[0][j] = 0;
}
}
}
for(int i = 1; i < matrix.length; i++){
for(int j = 1; j < matrix[i].length; j++){
if (matrix[0][j] == 0 || matrix[i][0] == 0) {
matrix[i][j] = 0;
}
}
}
if (iZero) {
for (int i = 0; i < matrix.length; ++i) matrix[i][0] = 0;
}
if (jZero) {
for (int i = 0; i < matrix[0].length; ++i) matrix[0][i] = 0;
}
}
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