46. 全排列

动态规划

class Solution {
    public List<List<Integer>> permute(int[] nums) {
       
        List<List<Integer>> result = new ArrayList<>();
        permute(nums ,  0 , nums.length -1, result);
        return result;
        
    }
    
    public void permute(int[] nums , int l , int h,List<List<Integer>> ls)
    {
        
       if(l == h)
       {
           List<Integer> ans = new ArrayList<>();
           for(int i : nums)
           {
               ans.add(i);
           }
           ls.add(ans);
           return;
       }
        else
        {
            
            for(int i = l ; i <= h ; i ++ )
            {
                swap(nums,i,l);
                permute(nums,l+1,h,ls);
                swap(nums,l,i);
                
            }
            
        }
       
        }
        
    
    public void swap(int[] nums , int f , int  t)
    {
        int temp = nums[f];
        nums[f] = nums[t];
        nums[t] = temp;
    }
}

47. 全排列 II

class Solution {
    public List<List<Integer>> permuteUnique(int[] nums) {
        List<List<Integer>> ans = new ArrayList<List<Integer>>();
        Arrays.sort(nums);
        boolean[] isuser = new boolean[nums.length];
        List<Integer> res = new ArrayList<>();
        permute(nums , isuser , nums.length -1 , ans,res);
        return ans;
    }
    public void permute(int[] nums , boolean[] isuser ,int h , List<List<Integer>> ans , List<Integer> res)
    {
        if(res.size() == nums.length )
        {
            ans.add(new ArrayList<>(res));
            return;
        }
        else
        {
            for(int i = 0 ; i <= h ; i++)
            {
                if(i != 0 &&nums[i] == nums[i-1] && isuser[i-1] == false) continue;
                if(isuser[i] == true)continue;
                isuser[i] = true;
                res.add(nums[i]);
                
                permute(nums,isuser,h,ans,res);
                res.remove(res.size()-1);
                isuser[i] = false;
            }
        }
        
    }
    public void swap(int[] nums , int j  , int t)
    {
        
        int temp = nums[j];
        nums[j] = nums[t];
        nums[t] = temp;
    
    }
    
}

标签：排列,nums,46,List,int,ans,new,permute
来源： https://blog.csdn.net/shenweiquanshuai/article/details/94052783