0832. Flipping an Image

# 832. Flipping an Image#

## 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`

## 解题思路 #

• 给定一个二进制矩阵，要求先水平翻转，然后再反转( 1→0 , 0→1 )。
• 简单题，按照题意先水平翻转，再反转即可。

## 代码 #

``````
package leetcode

func flipAndInvertImage(A [][]int) [][]int {
for i := 0; i < len(A); i++ {
for a, b := 0, len(A[i])-1; a < b; a, b = a+1, b-1 {
A[i][a], A[i][b] = A[i][b], A[i][a]
}
for a := 0; a < len(A[i]); a++ {
A[i][a] = (A[i][a] + 1) % 2
}
}
return A
}

``````

Sep 6, 2020