0040. Combination Sum II V1.0

Author: ChlZhYa

LeetCode/0040. Combination Sum II/src/Solution.java

@@ -0,0 +1,48 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Deque;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * @author changleamazing
+ * @date 2020/9/11 17:06 source: https://leetcode-cn.com/problems/combination-sum-ii/
+ **/
+public class Solution {
+    public List<List<Integer>> combinationSum2(int[] candidates, int target) {
+        if (candidates.length == 0) {
+            return null;
+        }
+        Arrays.sort(candidates);
+        List<List<Integer>> res = new ArrayList<>();
+        Deque<Integer> tempList = new LinkedList<>();
+        backtrace(candidates, 0, target, tempList, res);
+        return res;
+    }
+
+    private void backtrace(int[] candidates, int begin, int target, Deque<Integer> tempQueue, List<List<Integer>> res) {
+        if (target == 0) {
+            res.add(new ArrayList<>(tempQueue));
+            return;
+        }
+        for (int i = begin; i < candidates.length; i++) {
+            if (target < candidates[i]) {
+                break;
+            }
+            if (i > begin && candidates[i] == candidates[i - 1]) {
+                continue;
+            }
+
+            tempQueue.add(candidates[i]);
+            backtrace(candidates, i + 1, target - candidates[i], tempQueue, res);
+            tempQueue.removeLast();
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] candidates = {4, 4, 2, 1, 4, 2, 2, 1, 3};
+        Solution solution = new Solution();
+        solution.combinationSum2(candidates, 6);
+    }
+}