[LeetCode][JavaScript]Subsets II

Subsets II

Given a collection of integers that might contain duplicates, nums, return all possible subsets.

Note:

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

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

[
  [2],
  [1],
  [1,2,2],
  [2,2],
  [1,2],
  []
]

https://leetcode.com/problemset/algorithms/

---

上一题相同的思路，加上去重就可以了。

http://www.cnblogs.com/Liok3187/p/4733079.html

非递归：

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var subsetsWithDup = function(nums) {
    nums = nums.sort(sorting);
    var res = [[]], arr = [], visited = new Set();
    for(var i = 0; i < nums.length; i++){
        if(!visited.has(nums[i])){
            res.push([nums[i]]);
            visited.add(nums[i]);
        }
        arr.push({val : [nums[i]], pos : i});
    }
    getSets(arr);
    return res;

    function getSets(arr){
        var i, 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]);
                if(!visited.has(tmp.join('#'))){
                    res.push(tmp);
                    visited.add(tmp.join('#'));
                }
                nextArr.push({val : tmp, pos : j});
            }
        }
        if(nextArr.length > 0){
            getSets(nextArr);
        }
    }

    function sorting(a, b){
        return a - b;
    }
};

递归：

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var subsetsWithDup = function(nums) {
    nums = nums.sort(sorting), visited = new Set();
    var res = [];
    for(var i = 0; i < Math.pow(2, nums.length); i++){
        var str = padLeft(i, nums.length);
        var tmp = [];
        for(var j = 0; j < str.length; j++){
            if(str[j] === '1'){
                tmp.push(nums[j]);
            }
        }
        if(!visited.has(tmp.join('#'))){
            res.push(tmp);
            visited.add(tmp.join('#'));
        }
    }
    return res;
    
    function padLeft(num, len){
        var res = "", i = len;
        while(i--) res += '0';
        var tmp = parseInt(num).toString(2);
        res = res + tmp;
        return res.substring(tmp.length, res.length);
    }

    function sorting(a, b){
        return a -b;
    }
};