题目:输入一个数n,打印出它前n个数序列的全排列。
思路:
1、用STL库函数next_permutation,代码如下
//STL库函数法
vector> STL_function(vector &num)
{
vector> result;
do
{
result.push_back(num);
}while(next_permutation(num.begin(),num.end()));
return result;
}
//递归回溯法
void DG_function(vector &num,int start,int end,vector> &result1)
{
if(start==end)
result1.push_back(num);
for(int i=start;i<=end;i++)
{
swap(num[start],num[i]);
DG_function(num,start+1,end,result1);
swap(num[start],num[i]);
}
}
#include
#include
#include
using namespace std;
//STL库函数法
vector> STL_function(vector &num)
{
vector> result;
do
{
result.push_back(num);
}while(next_permutation(num.begin(),num.end()));
return result;
}
//递归回溯法
void DG_function(vector &num,int start,int end,vector> &result1)
{
if(start==end)
result1.push_back(num);
for(int i=start;i<=end;i++)
{
swap(num[start],num[i]);
DG_function(num,start+1,end,result1);
swap(num[start],num[i]);
}
}
void print(vector> v)
{
for(vector>::iterator iter=v.begin();iter!=v.end();iter++)
{
vector vv=*iter;
for(vector::iterator it=vv.begin();it!=vv.end();it++)
cout<<*it;
cout< num;
vector> result,result1;
cin>>n;
for(int i=1;i<=n;i++)
num.push_back(i);
result=STL_function(num);
DG_function(num,0,n-1,result1);
cout<<"STL_function : "<