From f630b021d02cb0ea8bd2cde21954f6b888042ac6 Mon Sep 17 00:00:00 2001
From: fanxb <fleyx20@outlook.com>
Date: Tue, 4 Jan 2022 23:21:29 +0800
Subject: [PATCH] add

---
 5.leetcode/src/com/fanxb/common/Q40.java | 26 +++++++++++++++---------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/5.leetcode/src/com/fanxb/common/Q40.java b/5.leetcode/src/com/fanxb/common/Q40.java
index d0ff0e3..f48501f 100644
--- a/5.leetcode/src/com/fanxb/common/Q40.java
+++ b/5.leetcode/src/com/fanxb/common/Q40.java
@@ -1,5 +1,6 @@
 package com.fanxb.common;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedList;
 import java.util.List;
@@ -12,26 +13,31 @@ public class Q40 {
         return res;
     }
 
-    private void deal(List<List<Integer>> res, List<Integer> cur, int i, int[] sources, int target) {
-        if (target < sources[i]) {
+    private void deal(List<List<Integer>> res, List<Integer> cur, int start, int[] sources, int target) {
+        if (start >= sources.length || target < sources[start]) {
             return;
         }
-        for (; i < sources.length; i++) {
+        for (int i = start; i < sources.length; i++) {
             if (sources[i] > target) {
                 return;
             }
-            List<Integer> temp = new LinkedList<>(cur);
-            temp.add(sources[i]);
-            if (sources[i] == target) {
-                res.add(temp);
-            } else {
-                deal(res, temp, i + 1, sources, target - sources[i]);
+            if (i > start && sources[i] == sources[i - 1]) {
+                //第二个重复的元素不需要进行后续操作
+                continue;
             }
+            cur.add(sources[i]);
+            if (sources[i] == target) {
+                res.add(new ArrayList<>(cur));
+            } else {
+                deal(res, cur, i + 1, sources, target - sources[i]);
+            }
+            //加入后删除当前元素，尝试下一个
+            cur.remove(cur.size() - 1);
         }
     }
 
     public static void main(String[] args) {
-        new Q40().combinationSum2(new int[]{10, 1, 2, 7, 6, 1, 5}, 8);
+        new Q40().combinationSum2(new int[]{2, 5, 2, 1, 2}, 5);
     }