leetcode-java-59. Spiral Matrix II

/*
Given an integer n, generate a square matrix filled with elements from 1 to n^2
in spiral order.
For example,
Given n = 3,
You should return the following matrix: [
[ 1, 2, 3 ],
[ 8, 9, 4 ],
[ 7, 6, 5 ]
]
*/
public class Solution {
public int[][] generateMatrix(int n) {
int[][] matrix = new int

;

int maxLoop = (n+1)/2,
begin = 1;

for(int i = 0;i < maxLoop;i++) {
// (i,i)--(i,n-1-i)
for(int j = i;j <= n-1-i;j++) {
matrix[i][j] = begin++;
}
// (i+1,n-1-i)--(m-1-i,n-1-i)
for(int j = i+1;j <= n-1-i;j++) {
matrix[j][n-1-i] = begin++;
}

// (m-1-i,n-i-2)--(m-1-i,i)
if(n-1-i > i) {
for(int j = n-i-2;j >= i;j--) {
matrix[n-1-i][j] = begin++;
}
}

// (m-i-2,i)--回到(i,i)
if(n-1-i > i) {
for(int j = n-i-2;j > i;j--) {
matrix[j][i] = begin++;
}
}
}

return matrix;
}
}