2021-04-01: Given a square matrix, adjust it to rotate 90 degrees clockwise. [[a,b,c],[d,e,f],[g,h,i]] becomes [[g,d,a],[h,e,b],[i,f,c ]].
Fu Da's answer 2021-04-01:
Four numbers exchange. Exchange the outer circle first, then the inner circle.
The code is written in golang. code show as below:
package main
import "fmt"
func main() {
matrix := [][]int{{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}}
printMatrix(matrix)
rotate(matrix)
printMatrix(matrix)
}
func rotate(matrix [][]int) {
matrixLen := len(matrix)
if matrixLen <= 1 {
return
}
a := 0 //左上行
b := 0 //左上列
c := matrixLen - 1 //右下行
d := c //右下列
//左上 右上 右下 左下
//a,b a,d c,d c,b
for a < c {
for j := a; j < c; j++ {
//四数交换
matrix[a][b+j], matrix[a+j][d], matrix[c][d-j], matrix[c-j][b] = matrix[a+j][d], matrix[c][d-j], matrix[c-j][b], matrix[a][b+j]
}
a++
b++
c--
d--
}
}
func printMatrix(matrix [][]int) {
for i := 0; i < len(matrix); i++ {
for j := 0; j < len(matrix[0]); j++ {
fmt.Print(matrix[i][j], "\t")
}
fmt.Println("")
}
fmt.Println("-----------")
}The execution results are as follows: