47.Permutations 1&2

1.Given A collection of numbers, return all possible permutations.

For example,
[1,2,3]The following permutations:
[1,2,3],,,,, [1,3,2] [2,1,3] [2,3,1] [3,1,2] and [3,2,1] .

2.

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

For example,
[1,1,2]The following unique permutations:
[1,1,2], [1,2,1] , and [2,1,1] .

Solution:dfs

1 2 3

12 13 21 23 32 31

123 132 213 231 321 312

 PackageLeetcode2;ImportJava.util.*; Public classpermutations { Public StaticArraylist<arraylist<integer>> Permute (int[] num) {ArrayList<ArrayList<Integer>> res=NewArraylist<arraylist<integer>>(); ArrayList<Integer> mem =NewArraylist<integer>(); intDeep=0; intLength=num.length; Booleanvisit[]=New Boolean[length];         DFS (RES,MEM,DEEP,NUM,VISIT,LENGTH); returnRes; }          Public Static voidDFS (arraylist<arraylist<integer>>Res, ArrayList<Integer> Mem,intDeepint[] num,Boolean[] Visit,intl) {//TODO auto-generated Method Stub        if(deep==l) {            if(!res.contains (NewArraylist<integer>(MEM))) {Res.add (NewArraylist<integer>(MEM)); }            return; }        if(deep<l) {             for(inti=0;i<l;i++){                if(i>0 && num[i-1] = = Num[i] &&!visit[i-1])                 Continue; if(!Visit[i])                {Mem.add (num[i]); Visit[i]=true; DFS (Res,mem,deep+1, num,visit,l); if(Mem.size () >0) {Mem.remove (mem.size ()-1); Visit[i]=false; }                }            }        }        if(deep>num.length)return; }     Public Static voidMain (string[] args) {//TODO auto-generated Method Stub     int[] a={1,2,3};    System.out.print (Permute (a)); }}

47.Permutations 1&2