[Leetcode] [JavaScript] Subsets

Subsets

Given a set of distinct integers, nums, return all possible subsets.

Note:

• Elements in a subset must is in non-descending order.
• The solution set must not contain duplicate subsets.

For example,
If nums = [1,2,3] , a solution is:

[  3],  [1], [2], [1,3], [+]  ,  [2,3], [up  ],  []]

All arranged.

First, the ingenious solution of non-recursion.

Examples of topics such as:

A total of 8 cases, if the three-bit binary representation, 1 for the election, 0 for the non-election, just 000 to 111.

The PadLeft method in the code converts the current number to a binary string of length equal to Nums.length, and the number of bits is less than 0.

1 /**2 * @param {number[]} nums3 * @return {number[][]}4  */5 varsubsets =function(nums) {6Nums =nums.sort (sorting);7     varres = [];8      for(vari = 0; I < Math.pow (2, nums.length); i++){9         varstr =PadLeft (i, nums.length);Ten         varTMP = []; One          for(varj = 0; J < Str.length; J + +){ A             if(Str[j] = = = ' 1 '){ - Tmp.push (Nums[j]); -             } the         } - Res.push (TMP); -     } -     returnRes; +      -     functionpadLeft (num, len) { +         varres = "", I =Len; A          while(i--) Res + = ' 0 '; at         varTMP = parseint (num). toString (2); -res = res +tmp; -         returnres.substring (Tmp.length, res.length); -     } -  -     functionsorting (A, b) { in         if(A >b) { -             return1; to}Else if(A <b) { +             return-1; -}Else{ the             return0; *         } $     }Panax Notoginseng};

High efficiency.

The conventional recursive method.

More difficult to describe, lifting chestnuts [1,2,3,4]

When recursion is reached, the next round of recursion is [all-in-one] and [1,2,4].

[1,2,3,4] will be handed back to [the].

When recursive to [1,3], the next round of recursion is [1,3,4].

And so on

1 /**2 * @param {number[]} nums3 * @return {number[][]}4  */5 varsubsets =function(nums) {6Nums =nums.sort (sorting);7     varres = [[]], arr = [];8      for(vari = 0; i < nums.length; i++){9 Res.push ([nums[i]]);Ten Arr.push ({val: [nums[i]], pos:i}); One     } A getsets (arr); -     returnRes; -  the     functionGetsets (arr) { -         varI, J, tmp, Nextarr = []; -          for(i = 0; i < arr.length; i++){ -              for(j = Arr[i].pos + 1; j < Nums.length; J + +){ +TMP = Arr[i].val.slice (0); - Tmp.push (Nums[j]); + Res.push (TMP); A Nextarr.push ({val:tmp, pos:j}); at             } -         } -         if(Nextarr.length > 0){ - getsets (Nextarr); -         } -     } in  -     functionsorting (A, b) { to         if(A >b) { +             return1; -}Else if(A <b) { the             return-1; *}Else{ $             return0;Panax Notoginseng         } -     } the}

[Leetcode] [JavaScript] Subsets