From 40c06155f9e65e3525100ac6aff6f3ce6aeb8dac Mon Sep 17 00:00:00 2001
From: hutbzc <3260189532@qq.com>
Date: Tue, 1 Feb 2022 23:04:07 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880139.=E5=8D=95?=
 =?UTF-8?q?=E8=AF=8D=E6=8B=86=E5=88=86.md=EF=BC=89=EF=BC=9A=E5=A2=9E?=
 =?UTF-8?q?=E5=8A=A0Java=E5=9B=9E=E5=9B=9E=E6=BA=AF+=E8=AE=B0=E5=BF=86?=
 =?UTF-8?q?=E5=8C=96=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 ...25\350\257\215\346\213\206\345\210\206.md" | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git "a/problems/0139.\345\215\225\350\257\215\346\213\206\345\210\206.md" "b/problems/0139.\345\215\225\350\257\215\346\213\206\345\210\206.md"
index e24ffc1a89..1653a81a14 100644
--- "a/problems/0139.\345\215\225\350\257\215\346\213\206\345\210\206.md"
+++ "b/problems/0139.\345\215\225\350\257\215\346\213\206\345\210\206.md"
@@ -248,6 +248,36 @@ class Solution {
         return valid[s.length()];
     }
 }
+
+// 回溯法+记忆化
+class Solution {
+    public boolean wordBreak(String s, List<String> wordDict) {
+        Set<String> wordDictSet = new HashSet(wordDict);
+        int[] memory = new int[s.length()];
+        return backTrack(s, wordDictSet, 0, memory);
+    }
+    
+    public boolean backTrack(String s, Set<String> wordDictSet, int startIndex, int[] memory) {
+        // 结束条件
+        if (startIndex >= s.length()) {
+            return true;
+        }
+        if (memory[startIndex] != 0) {
+            // 此处认为：memory[i] = 1 表示可以拼出i 及以后的字符子串， memory[i] = -1 表示不能
+            return memory[startIndex] == 1 ? true : false;
+        }
+        for (int i = startIndex; i < s.length(); ++i) {
+            // 处理 递归 回溯       循环不变量：[startIndex, i + 1)
+            String word = s.substring(startIndex, i + 1);
+            if (wordDictSet.contains(word) && backTrack(s, wordDictSet, i + 1, memory)) {
+                memory[startIndex] = 1;
+                return true;
+            }
+        }
+        memory[startIndex] = -1;
+        return false;
+    }
+}
 ```
 
 Python：