59. 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 ]
]

思路

这道题目又是螺旋遍历，思路和前面一篇博客：Spiral Matrix一模一样
就不多说了，直接上代码：

代码

class Solution {public:    vector<vector<int>> generateMatrix(int n) {        //生成n*n的数组        vector<int> tmp(abs(n),1);        vector<vector<int>> matrix;        if (n==0)            return matrix;        for(int j=0;j<abs(n);j++)            matrix.push_back(tmp);        int rowbegin = 0,rowend=matrix.size()-1,colbegin=0,colend = matrix[0].size()-1;         int num =1;        while(rowbegin<=rowend&&colbegin<=colend)//大循环        {            for(int i=colbegin;i<=colend;i++)//从左往右            {                matrix[rowbegin][i] =num ;                num++;            }            rowbegin++;            for(int i=rowbegin;i<=rowend;i++)//从上至下            {                matrix[i][colend] =num;                num++;            }            colend--;            if(rowbegin<=rowend)            {                for(int i=colend;i>=colbegin;i--)//从右往左                {                    matrix[rowend][i] = num;                    num++;                }            }            rowend--;            if(colbegin<=colend)            {                for(int i=rowend;i>=rowbegin;i--)//从下往上                {                    matrix[i][colbegin]=num;                    num++;                }            }            colbegin++;        }                return matrix;     }};