[每日 LeetCode] 832. Flipping an Image

Description:

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

思路：本题要求图像的翻转，意思是将二维数组中的数组先水平翻转，然后再对每个元素取反。C++ 中有数组翻转的函数 reverse，直接调用即可。

C++ 代码

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

运行时间：12ms

运行内存：9.4M