|
| 1 | + |
| 2 | +>仰望星空的人,不应该被嘲笑 |
| 3 | + |
| 4 | +## 题目描述 |
| 5 | +给定一个无重复元素的数组 `candidates` 和一个目标数 `target` ,找出 `candidates` 中所有可以使数字和为 `target` 的组合。 |
| 6 | + |
| 7 | +`candidates` 中的数字可以无限制重复被选取。 |
| 8 | + |
| 9 | +说明: |
| 10 | + |
| 11 | +```javascript |
| 12 | +所有数字(包括 target)都是正整数。 |
| 13 | +解集不能包含重复的组合。 |
| 14 | +``` |
| 15 | + |
| 16 | +示例 1: |
| 17 | + |
| 18 | +```javascript |
| 19 | +输入:candidates = [2,3,6,7], target = 7, |
| 20 | +所求解集为: |
| 21 | +[ |
| 22 | + [7], |
| 23 | + [2,2,3] |
| 24 | +] |
| 25 | +``` |
| 26 | + |
| 27 | +示例 2: |
| 28 | + |
| 29 | +```javascript |
| 30 | +输入:candidates = [2,3,5], target = 8, |
| 31 | +所求解集为: |
| 32 | +[ |
| 33 | + [2,2,2,2], |
| 34 | + [2,3,3], |
| 35 | + [3,5] |
| 36 | +] |
| 37 | +``` |
| 38 | + |
| 39 | + |
| 40 | + |
| 41 | +提示: |
| 42 | + |
| 43 | +```javascript |
| 44 | +1 <= candidates.length <= 30 |
| 45 | +1 <= candidates[i] <= 200 |
| 46 | +candidate 中的每个元素都是独一无二的。 |
| 47 | +1 <= target <= 500 |
| 48 | +``` |
| 49 | + |
| 50 | +来源:力扣(LeetCode) |
| 51 | +链接:https://leetcode-cn.com/problems/combination-sum |
| 52 | +著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。 |
| 53 | + |
| 54 | + |
| 55 | + |
| 56 | +## 解题思路 |
| 57 | +这道题是组合题,但是这道题有意思的是当前元素可以重复无限制选取,那么我们可以改一下另外一道组合题的思路,下一层也从 `i`开始即可,然后本题元素重复,那么我们不需要进行排序然后剪枝了。 |
| 58 | + |
| 59 | +```javascript |
| 60 | +// 当前元素可以无限制选取,下一层也从i开始取 |
| 61 | +dfs(t.slice(),i,sum+candidates[i]); |
| 62 | +``` |
| 63 | + |
| 64 | + |
| 65 | +<a href="https://leetcode-cn.com/problems/combination-sum/solution/shou-hua-tu-jie-zu-he-zong-he-combination-sum-by-x/">参考xiao_ben_zhu图解</a> |
| 66 | + |
| 67 | +```javascript |
| 68 | +var combinationSum = function(candidates, target) { |
| 69 | + let res = []; |
| 70 | + let dfs = (t,start,sum) => { |
| 71 | + if(sum >= target){ // 防止爆掉 |
| 72 | + if(sum === target){ |
| 73 | + res.push(t); |
| 74 | + } |
| 75 | + return; |
| 76 | + } |
| 77 | + for(let i=start;i<candidates.length;i++){ |
| 78 | + t.push(candidates[i]); |
| 79 | + // 当前元素可以无限制选取,下一层也从i开始取 |
| 80 | + dfs(t.slice(),i,sum+candidates[i]); |
| 81 | + t.pop(); |
| 82 | + } |
| 83 | + } |
| 84 | + dfs([],0,0); |
| 85 | + return res; |
| 86 | +}; |
| 87 | +``` |
| 88 | + |
| 89 | + |
| 90 | + |
| 91 | +## 最后 |
| 92 | +文章产出不易,还望各位小伙伴们支持一波! |
| 93 | + |
| 94 | +往期精选: |
| 95 | + |
| 96 | +<a href="https://github.com/Chocolate1999/Front-end-learning-to-organize-notes">小狮子前端の笔记仓库</a> |
| 97 | + |
| 98 | +<a href="https://yangchaoyi.vip/">访问超逸の博客</a>,方便小伙伴阅读玩耍~ |
| 99 | + |
| 100 | + |
| 101 | + |
| 102 | +```javascript |
| 103 | +学如逆水行舟,不进则退 |
| 104 | +``` |
| 105 | + |
| 106 | + |
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