40. Combination Sum II（js）

40. Combination Sum II

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.

Each number in candidates may only be used once in the combination.

Note:

• All numbers (including target) will be positive integers.
• The solution set must not contain duplicate combinations.

Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8,
A solution set is:
[
  [1, 7],
  [1, 2, 5],
  [2, 6],
  [1, 1, 6]
]

Example 2:

Input: candidates = [2,5,2,1,2], target = 5,
A solution set is:
[
  [1,2,2],
  [5]
]
题意：获取所有的排列组合，使得所有项加起来等于target,可选项不能重复，结果不能重复
代码如下：

/**
 * @param {number[]} candidates
 * @param {number} target
 * @return {number[][]}
 */
var combinationSum2 = function(candidates, target) {
    var res={};
    var curr=[];
    candidates.sort((a,b)=>a-b);
    backTrack(res,curr,candidates,target,0);
    return Object.values(res);
};
function backTrack(res,curr,candidates,target,start){

    if(target>0){
        for(var i=start;i<candidates.length && target>=candidates[i];i++){
            curr.push(candidates[i]);
            backTrack(res,curr,candidates,target-candidates[i],i+1);
            curr.pop();
        }
    }else if(target==0){
        let str=curr.join('')
        res[str]=[...curr];
    }
}