How to Flip a Binary Matrix in Java
The challenge
Given a binary matrix A
, we want to flip the image horizontally, then invert it, and return the resulting image.
To flip an image horizontally means that each row of the image is reversed. For example, flipping [1, 1, 0]
horizontally results in [0, 1, 1]
.
To invert an image means that each is replaced by `1`, and each `1` is replaced by
. For example, inverting [0, 1, 1]
results in [1, 0, 0]
.
Example 1:
Example 2:
Notes:
1 <= A.length = A[0].length <= 20
0 <= A[i][j] <= 1
The solution in Java code
class Solution {
public int[][] flipAndInvertImage(int[][] A) {
for(int i = 0; i < A.length; i ++) {
int j = 0;
int k = A[i].length - 1;
while(j <= k) {
if(A[i][j] == 1) A[i][j] = 0;
else A[i][j] = 1;
if(k > j) {
if(A[i][k] == 1) A[i][k] = 0;
else A[i][k] = 1;
int temp = A[i][j];
A[i][j] = A[i][k];
A[i][k] = temp;
}
j++;
k--;
}
}
return A;
}
}