第73題，題目如下:
Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0‘s.
You must do it in place.
Example 1:
Input: matrix = [[1,1,1],[1,0,1],[1,1,1]] Output: [[1,0,1],[0,0,0],[1,0,1]]
Example 2:
Input: matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]] Output: [[0,0,0,0],[0,4,5,0],[0,3,1,0]]
Constraints:
m == matrix.lengthn == matrix[0].length1 <= m, n <= 200-231 <= matrix[i][j] <= 231 - 1
Follow up:
- A straightforward 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?
把所有的0找出來，然後標記出為0的行和列(x, y)。接著只要判斷有標記0發生的行和列(x,y)，即可將十字形的0給設定出來。
“`
public void setZeroes(int[][] matrix) {
int rows = matrix.length;
int cols = matrix[0].length;
// Arrays to mark rows and columns to be zeroed
boolean[] zeroRows = new boolean[rows];
boolean[] zeroCols = new boolean[cols];
// Traverse the matrix to mark rows and columns to be zeroed
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
if (matrix[i][j] == 0) {
zeroRows[i] = true;
zeroCols[j] = true;
}
}
}
for (int j = 0; j < cols; j++) {
if (zeroRows[i] || zeroCols[j]) {
matrix[i][j] = 0;
}
}
}
“`
