Permutations

Given a collection of numbers, return all possible permutations.

For example,

[1,2,3] have the following permutations:

[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

Permutations II

 

Given a collection of numbers that might contain duplicates, return all possible unique permutations.

For example,

[1,1,2] have the following unique permutations:

[1,1,2], [1,2,1], and [2,1,1].

全排列问题

第二个题目基于第一题。第二题给的数组中还有可能相等的元素。

请參照 

题一代码

class Solution {public:    vector
     
      
       > permute(vector
       
        & nums) {       vector
        
         
          >v;       v.clear();       vector
          
           a; next_c(v,nums.size(),a,nums,0); return v; } void next_c(vector
           
            
             >&v,int n,vector
             
              & a,vector
              
               & b,int cur) /// b[]中的数能够同样 { if(cur==n){ v.push_back(a); } else{ for(int i=0;i
              
             
            
           
          
         
        
       
      
     

题二代码。当然能够过题一。

class Solution {public:    vector
     
      
       >v;    vector
       
        
         > permuteUnique(vector
         
          & nums) {        v.clear();       vector
          
           a;a.clear(); sort(nums.begin(),nums.end()); next_c(nums.size(),a,nums,0); return v; } void next_c(int n,vector
           
            & a,vector
            
             & b,int cur) /// b[]中的数能够同样{ if(cur==n){ v.push_back(a); } else{ for(int i=0;i