Link:https://leetcode.com/problems/combination-sum/

    1. /**
    2.  * @param {number[]} candidates
    3.  * @param {number} target
    4.  * @return {number[][]}
    5.  */
    6. var combinationSum = function(candidates, target) {
    7.   let rst = [], local = [];
    8.   backtrack(rst, local, candidates, target);
    9.   return rst;
    10. };
    12. function backtrack(rst, local, candidates, target) {
    13.   if(equal(local, target) && !judgeArrEqual(rst, local)) rst.push(local);
    14.   else {
    15.     for(let i=0; i<candidates.length; i++) {
    16.       local.push(candidates[i]);
    17.       let nextLocal = local.slice(0);
    18.       if(constraint(local, target)) {
    19.         backtrack(rst, nextLocal, candidates, target);
    20.       }
    21.       local.pop();
    22.     }
    23.   }
    24. }
    26. function judgeArrEqual(arr, arr2) {
    27.   let ar2 = arr2.slice(0).sort();
    28.   return arr.some(ele => {
    29.     let ar1 = ele.slice(0).sort();
    30.     if(ar1.toString() === ar2.toString()) return true;
    31.   });
    32. }
    34. function equal(arr, target) {
    35.   let sum =0;
    36.   if(arr.length !== 0) {
    37.     sum = arr.reduce((acc, cur) => (acc+cur));
    38.   }
    39.   if(sum === target) return true;
    40.   else return false;
    41. }
    43. function constraint(arr, target) {
    44.   let sum =0;
    45.   if(arr.length !== 0) {
    46.     sum = arr.reduce((acc, cur) => (acc+cur));
    47.   }
    48.   if(sum > target) return false;
    49.   else return true;
    50. }