leetcode_59题——Spiral Matrix II（数组）

Spiral Matrix II

Total Accepted: 28996 Total Submissions: 91437My Submissions
Question Solution

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 ]
]

Hide Tags
Array

这道题，需要将1...到n^2的所有数以螺旋的方式写到数组中，我采用的是一圈一圈的从外往里写，这个思路比较直接，而且时间复杂度为O(n),在可接受的范围之内

#include<iostream>
#include<vector>
using namespace std;

vector<vector<int> > generateMatrix(int n) {
vector<vector<int> >last_result;
vector<int> temp;
if(n<=0)
return last_result;
if(n==1)
{
temp.push_back(1);
last_result.push_back(temp);
return last_result;
}
for(int j=0;j<n;j++)
temp.push_back(0);
for(int i=0;i<n;i++)
last_result.push_back(temp);

int quan=n;
int start_quan=1;
int x1=0,x2=0;
int y1=0,y2=n-1;
int m1=n-1,m2=n-1;
int n1=n-1,n2=0;
while(quan>0)
{
for(int i=x2;i<=x2+quan-2;i++)
{
last_result[x1][i]=start_quan;
start_quan++;
}
for(int i=y1;i<=y1+quan-2;i++)
{
last_result[i][y2]=start_quan;
start_quan++;
}
for(int i=m2;i>=m2-(quan-2);i--)
{
last_result[m1][i]=start_quan;
start_quan++;
}
for(int i=n1;i>=n1-(quan-2);i--)
{
last_result[i][n2]=start_quan;
start_quan++;
}
quan-=2;
x1++;x2++;
y1++;y2--;
m1--;m2--;
n1--;n2++;

if(quan==1)
{
last_result[x1][x2]=start_quan;
break;
}
}
return last_result;
}

int main()
{
vector<vector<int> > vec;
int n=4;
vec=generateMatrix(n);
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
cout<<vec[i][j]<<' ';
cout<<endl;
}

}