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CombinationSumII.java
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CombinationSumII.java
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package src.java.medium.backtracking;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class CombinationSumII {
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
Arrays.sort(candidates);
List<Integer> list = new ArrayList<>();
List<List<Integer>> ret = new ArrayList<>();
combinationSum2(candidates, target, 0, list, ret);
return ret;
}
private void combinationSum2(int[] candidates, int target, int start, List<Integer> list, List<List<Integer>> ret) {
if (target == 0) {
List<Integer> l = new ArrayList<>(list);
ret.add(l);
return;
}
for (int i=start; i<candidates.length && candidates[i]<=target; i++) {
if (i>start && candidates[i]==candidates[i-1])
continue;
list.add(candidates[i]);
combinationSum2(candidates, target-candidates[i], i+1, list, ret);
list.remove(list.size()-1);
}
}
// Legacy
public ArrayList<ArrayList<Integer>> combinationSum2Legacy(int[] candidates, int target) {
// Start typing your Java solution below
// DO NOT write main() function
if (candidates == null) return null;
Arrays.sort(candidates);
ArrayList<ArrayList<Integer>> ret = combinationSum(candidates, 0, target);
return ret;
}
public ArrayList<ArrayList<Integer>> combinationSum(int[] candidates, int start, int target) {
ArrayList<ArrayList<Integer>> ret = new ArrayList<ArrayList<Integer>>();
for (int i=start; i<candidates.length; i++){
if (i>start && candidates[i]==candidates[i-1]) continue;
if (candidates[i] == target){
ArrayList<Integer> list = new ArrayList<Integer>();
list.add(target);
ret.add(list);
}
else if (candidates[i] < target){
ArrayList<ArrayList<Integer>> temp = combinationSum(candidates, i+1, target-candidates[i]);
if (!temp.isEmpty()){
for(ArrayList<Integer> list : temp)
list.add(0, candidates[i]);
ret.addAll(temp);
}
}
else
break;
}
return ret;
}
}