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Copy path39_combinationSum.java
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53 lines (47 loc) · 1.77 KB
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public class Solution {
public List<List<Integer>> combinationSum(int[] candidates, int target) {
List<List<Integer>> res = new ArrayList<List<Integer>>();
List<Integer> list = new ArrayList<Integer>();
Arrays.sort(candidates);
helper(candidates, target, 0, res, list);
return res;
}
public void helper(int[] candidates, int target, int pos, List<List<Integer>> res, List<Integer> list){
if(target < 0) return;
if(target == 0){
res.add(new ArrayList<Integer>(list)); //如果不在下面make a copy那就在这里make a copy！！！
return;
}
for(int i = pos; i < candidates.length; i++){
list.add(candidates[i]);
target-=candidates[i];
helper(candidates, target, i, res, list);
list.remove(list.size()-1);
target+=candidates[i];
}
}
}
public class Solution {
public List<List<Integer>> combinationSum(int[] candidates, int target) {
List<List<Integer>> result = new LinkedList<List<Integer>>();
List<Integer> list = new LinkedList<Integer>();
Arrays.sort(candidates);
dfs(candidates, target, result, list, 0);
return result;
}
public void dfs(int[] candidates, int target, List<List<Integer>> result, List<Integer> list, int index){
if(target == 0){
result.add(list);
return;
}
else if(target < 0){
return;
} else{
for(int i = index; i < candidates.length; i++){
List<Integer> copy = new LinkedList<Integer>(list);
copy.add(candidates[i]);
dfs(candidates, target-candidates[i], result, copy, i);
}
}
}
}