[LeetCode] 832. Flipping an Image

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

题目大意：

一张图片用一个只包含0或1的元素组成的矩阵表示，将这个图片倒置并翻转。

倒置：如果元素是0就变成1，如果元素是1则变成0；

翻转：水平方向上中心对称。

使用最简单的双层循环依次对元素进行处理，并放到新的结果数组当中。这里对元素的倒置使用的异或。异或：相同则0，不同则1。

代码如下：

class Solution {
public:
    vector<vector<int>> flipAndInvertImage(vector<vector<int>>& A) {
        vector<vector<int>> res(A.size(),vector<int>(A[0].size()));
        for(int i=0;i<A.size();++i){
            for(int j=0;j<A[i].size();++j){
                res[i][A[i].size()-1-j]=A[i][j]^1;
            }
        }
        return res;
    }
};