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/**

* 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 0 is replaced by 1, and each 1 is

* replaced by 0. For example, inverting [0, 1, 1] results in [1, 0, 0].

*

* Example 1:

* Input: [[1,1,0],[1,0,1],[0,0,0]]

* Output: [[1,0,0],[0,1,0],[1,1,1]]

* Explanation: First reverse each row: [[0,1,1],[1,0,1],[0,0,0]].

* Then, invert the image: [[1,0,0],[0,1,0],[1,1,1]]

*

* Example 2:

* Input: [[1,1,0,0],[1,0,0,1],[0,1,1,1],[1,0,1,0]]

* Output: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]

* Explanation: First reverse each row: [[0,0,1,1],[1,0,0,1],[1,1,1,0],[0,1,0,1]].

* Then invert the image: [[1,1,0,0],[0,1,1,0],[0,0,0,1],[1,0,1,0]]

*

* Notes:

* 1 <= A.length = A[0].length <= 20

* 0 <= A[i][j] <= 1

*/

public class FlippingAnImage832 {

public int[][] flipAndInvertImage(int[][] A) {

int N = A.length;

int[][] res = new int[N][N];

for (int i=0; i<N; i++) {

for (int j=0; j<N; j++) {

res[i][j] = 1 - A[i][N - j-1];

}

}

return res;

}

public int[][] flipAndInvertImage2(int[][] A) {

for (int i=0; i<A.length; i++) {

reverseAndFlip(A[i]);

}

return A;

}

private void reverseAndFlip(int[] row) {

int lo = 0;

int hi = row.length - 1;

while (lo <= hi) {

swapAndFlip(row, lo++, hi--);

}

}

private void swapAndFlip(int[] row, int i, int j) {

if (i == j) {

row[i] = 1 - row[i];

return;

}

int tmp = row[i];

row[i] = 1 - row[j];

row[j] = 1- tmp;

}

}