[Leetcode] 832. flipping-an-image (simulation) [simple]

link

https://leetcode-cn.com/problems/flipping-an-image/

time consuming

Problem solving: 29 min
Problem solving: 4 min

Title

Given a binary matrix A, we want to flip the image horizontally first, then invert the image and return the result.

To flip a picture horizontally is to flip each line of the picture, that is, reverse the order. For example, the result of horizontally flipping [1, 1, 0] is [0, 1, 1].

Inverting the picture means that all 0s in the picture are replaced by 1s, and all 1s are replaced by 0s. For example, the result of reversing [0, 1, 1] is [1, 0, 0].

prompt:

• 1 <= A.length = A[0].length <= 20
• 0 <= A[i][j] <= 1

Ideas

The simulated question is enough, see the code for details.

Time complexity: $O(n^2)$

AC code

class Solution {
    
    
public:
    vector<vector<int>> flipAndInvertImage(vector<vector<int>>& A) {
    
    
        int n = A.size();
        for(int i = 0; i < n; ++i) {
    
    
            for(int j = 0; j < n/2; ++j) {
    
    
                swap(A[i][j], A[i][n-j-1]);
            }
            for(int j = 0; j < n; ++j) {
    
    
                A[i][j] = (!A[i][j]);
            }
        }
        return A;
    }
};