Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
For example,
Given n = 3,
You should return the following matrix:
[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ] ]
class Solution { public: vector<vector<int> > generateMatrix(int n) { vector<vector<int> > res(n,vector<int>(n,0)); int dx[] = {0,1,0,-1}; int dy[] = {1,0,-1,0}; int cnt = 1,step = 0,x = 0 , y = 0; while(cnt <= n*n){ step%=4; res[x][y] = cnt++; if(x+dx[step] >=n || x+dx[step] < 0 || y+dy[step] >=n || y+dy[step] < 0 || res[x+dx[step]][y+dy[step]]) step++; x+=dx[step%4];y+=dy[step%4]; } return res; } };
Leetcode Spiral Matrix II,布布扣,bubuko.com
原文：http://www.cnblogs.com/xiongqiangcs/p/3809013.html