螺旋矩阵

题目链接

class Solution {
public:vector<vector<int>> generateMatrix(int n) {vector<vector<int>>res(n, vector<int>(n, 0));int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};  //方向偏移数组int x = 0, y = 0;  //当前位置for(int i = 1, d = 0; i <= n*n; i++){res[x][y] = i; int a = x + dx[d], b = y + dy[d]; if(a <0 || a == n || b < 0 || b == n || res[a][b]){  //出界或者该位置已经被走过d = (d + 1) % 4;   //更改方向a = x + dx[d], b = y + dy[d];  //下一个要走的位置}x = a, y = b;    }return res;}
};