832.Flipping an Image（翻转图像）

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本文介绍了一种算法，该算法接收一个二进制矩阵，首先水平翻转矩阵中的每一行，然后对每个元素进行取反操作。通过具体示例展示了操作过程及最终结果。

题目

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

题目意思

根据给出的例子可以发现规则：
翻转图像矩阵的每一行，并且对每一个元素取反

代码

class Solution {
public:
    vector<vector<int>> flipAndInvertImage(vector<vector<int>>& A) {
        vector<vector<int>> result;
        vector<int> mid;
        for( int i = 0 ; i < A.size() ; ++ i ){
            for( int j = A[i].size() - 1 ; j >= 0 ; -- j){
                //通过与1异或得到取反，让j从末尾开始实现矩阵行的翻转
                mid.push_back( A[i][j] ^ 1 );
            }
            result.push_back( mid );
            mid.clear();
        }
        return result;
    }
};