leetcode：Spiral Matrix II

leetcode：Spiral Matrix II 

题目：

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 ]
]

即，给定矩阵大小，返回螺旋矩阵

c++实现:

#include <iostream>#include <vector>using namespace std;vector<vector<int> > generateMatrix(int n){vector< vector<int> > matrix(n, vector<int>(n));if (n == 0) return matrix;int beginX = 0, endX = n - 1;int beginY = 0, endY = n - 1;int num = 1;while (true) {for (int j = beginX; j <= endX; ++j) matrix[beginY][j] = num++;if (++beginY > endY) break;for (int i = beginY; i <= endY; ++i) matrix[i][endX] = num++;if (beginX > --endX) break;for (int j = endX; j >= beginX; --j) matrix[endY][j] = num++;if (beginY > --endY) break;for (int i = endY; i >= beginY; --i) matrix[i][beginX] = num++;if (++beginX > endX)break;}return matrix;}int main(){vector<vector<int>> vec;int n=3;vec=generateMatrix(n);vector<vector<int>>::iterator pp;      vector<int>::iterator it;      for(pp=vec.begin();pp<vec.end();pp++)      {          for (it=(*pp).begin();it<(*pp).end();it++)          {              cout<<*it<<" ";          }          cout<<endl;      }  return 0;}

测试结果：