leetcode[59]Spiral Matrix II

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:
void generate1(int icount, vector<vector<int>> &res, int left, int right, int up, int down)
{
/*
if (icount==res.size()*res[0].size())
return;
*/
if (left>right||up>down)
return;
if (up==down)
{
for (int j=left;j<=right;j++)
{
icount++;
res[up][j]=icount;
}
return;
}
if (left==right)
{
for (int i=up;i<=down;i++)
{
icount++;
res[i][left]=icount;
}
return;
}
for (int j=left;j<right;j++)
{
icount++;
res[up][j]=icount;
}
for (int i=up;i<down;i++)
{
icount++;
res[i][right]=icount;
}
for (int j=right;j>left;j--)
{
icount++;
res[down][j]=icount;
}
for(int i=down;i>up;i--)
{
icount++;
res[i][left]=icount;
}
generate1(icount, res, left+1, right-1, up+1, down-1);
}
vector<vector<int> > generateMatrix(int n)
{
vector<vector<int>> res;
if(n==0)return res;
vector<int> temp;
temp.insert(temp.end(),n,INT_MIN);
res.insert(res.end(),n,temp);
generate1(0,res,0,n-1,0,n-1);
return res;
}
};