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;
}
};