Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
For example,
Given n = 3,
[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ] ]
class Solution {
public:
vector<vector<int> > generateMatrix(int n) {
static int dir[][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
vector<vector<int> > ans(n, vector<int>(n));
int num = 1;
int k = 0;
int x = -1, y = 0;
while (n) {
if (k & 1)
--n;
for (int i=0; i<n; i++) {
x += dir[k][0];
y += dir[k][1];
ans[y][x] = num++;
}
k = (k+1) & 3;
}
return ans;
}
};原文：http://blog.csdn.net/elton_xiao/article/details/44702867