Add 40_Combination_Sum_II.java

Author: Sean Prashad

Backtracking/40_Combination_Sum_II.java

@@ -0,0 +1,32 @@
+class Solution {
+ public List<List<Integer>> combinationSum2(int[] candidates, int target) {
+ if (candidates == null || candidates.length == 0) {
+ return Collections.emptyList();
+ }
+
+ Arrays.sort(candidates);
+
+ List<List<Integer>> result = new ArrayList<>();
+ dfs(candidates, target, 0, new ArrayList<>(), result);
+ return result;
+ }
+
+ private void dfs(int[] candidates, int target, int idx, List<Integer> tempResult, List<List<Integer>> result) {
+ if (target < 0) {
+ return;
+ }
+ if (target == 0) {
+ result.add(new ArrayList<>(tempResult));
+ return;
+ }
+
+ for (int i = idx; i < candidates.length; i++) {
+ if (i > idx && candidates[i] == candidates[i - 1]) {
+ continue;
+ }
+ tempResult.add(candidates[i]);
+ dfs(candidates, target - candidates[i], i + 1, tempResult, result);
+ tempResult.remove(tempResult.size() - 1);
+ }
+ }
+}