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【问题】
Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.
The same repeated number may be chosen from C unlimited number of times.
Note:
For example, given candidate set 2,3,6,7 and target 7,
A solution set is: [7] [2, 2, 3]
【分析】
1.考虑用DFS的方式去解决该问题
2.由于需要考虑集合内的记录有序，且无重复，在递归的时候设置一个level
【算法实现】
public class Solution { List<List<Integer>> res; List<Integer> temp; public List<List<Integer>> combinationSum(int[] candidates, int target) { res=new ArrayList<List<Integer>>(); temp=new ArrayList<Integer>(); Arrays.sort(candidates); //考虑集合内的元素有序 getCombination(candidates,target,0,0); return res; } public void getCombination(int[] candidates,int target,int sum,int level) { if(sum>target) return; if(target==sum) { res.add(new ArrayList<Integer>(temp)); return; } for(int i=level;i<candidates.length;i++) { sum+=candidates[i]; temp.add(candidates[i]); getCombination(candidates,target,sum,i); temp.remove(temp.size()-1); sum-=candidates[i]; } } }
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原文地址：http://www.cnblogs.com/hwu2014/p/4444676.html
