From fec810214865a4da7766c58019f7d0d79cfde93a Mon Sep 17 00:00:00 2001
From: MaoLongLong <382084620@qq.com>
Date: Fri, 30 Apr 2021 17:45:35 +0800
Subject: [PATCH] feat: add solutions to leetcode problem: No.0377. Combination
 Sum IV

---
 .../0377.Combination Sum IV/README.md         | 27 +++++++++++++++--
 .../0377.Combination Sum IV/README_EN.md      | 27 +++++++++++++++--
 .../0377.Combination Sum IV/Solution.java     | 29 +++++--------------
 .../0377.Combination Sum IV/Solution.py       |  9 ++++++
 4 files changed, 67 insertions(+), 25 deletions(-)
 create mode 100644 solution/0300-0399/0377.Combination Sum IV/Solution.py

diff --git a/solution/0300-0399/0377.Combination Sum IV/README.md b/solution/0300-0399/0377.Combination Sum IV/README.md
index 6c41bd0aead8b..6671c278bc8bd 100644
--- a/solution/0300-0399/0377.Combination Sum IV/README.md	
+++ b/solution/0300-0399/0377.Combination Sum IV/README.md	
@@ -56,6 +56,8 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+简单动态规划，`dp[i]` 表示总和为 `i` 的元素组合的个数。
+
 <!-- tabs:start -->
 
 ### **Python3**
@@ -63,7 +65,15 @@
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def combinationSum4(self, nums: List[int], target: int) -> int:
+        dp = [0 for i in range(target + 1)]
+        dp[0] = 1
+        for i in range(1, target + 1):
+            for num in nums:
+                if i - num >= 0:
+                    dp[i] += dp[i - num]
+        return dp[target]
 ```
 
 ### **Java**
@@ -71,7 +81,20 @@
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class Solution {
+    public int combinationSum4(int[] nums, int target) {
+        int[] dp = new int[target + 1];
+        dp[0] = 1;
+        for (int i = 1; i <= target; i++) {
+            for (int num : nums) {
+                if (i - num >= 0) {
+                    dp[i] += dp[i - num];
+                }
+            }
+        }
+        return dp[target];
+    }
+}
 ```
 
 ### **...**
diff --git a/solution/0300-0399/0377.Combination Sum IV/README_EN.md b/solution/0300-0399/0377.Combination Sum IV/README_EN.md
index 38483fa5db6b9..ff0c0d94c7eac 100644
--- a/solution/0300-0399/0377.Combination Sum IV/README_EN.md	
+++ b/solution/0300-0399/0377.Combination Sum IV/README_EN.md	
@@ -49,18 +49,41 @@ Note that different sequences are counted as different combinations.
 
 ## Solutions
 
+`dp[i]` represents the number of element combinations whose sum is `i`.
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 ```python
-
+class Solution:
+    def combinationSum4(self, nums: List[int], target: int) -> int:
+        dp = [0 for i in range(target + 1)]
+        dp[0] = 1
+        for i in range(1, target + 1):
+            for num in nums:
+                if i - num >= 0:
+                    dp[i] += dp[i - num]
+        return dp[target]
 ```
 
 ### **Java**
 
 ```java
-
+class Solution {
+    public int combinationSum4(int[] nums, int target) {
+        int[] dp = new int[target + 1];
+        dp[0] = 1;
+        for (int i = 1; i <= target; i++) {
+            for (int num : nums) {
+                if (i - num >= 0) {
+                    dp[i] += dp[i - num];
+                }
+            }
+        }
+        return dp[target];
+    }
+}
 ```
 
 ### **...**
diff --git a/solution/0300-0399/0377.Combination Sum IV/Solution.java b/solution/0300-0399/0377.Combination Sum IV/Solution.java
index 4ce9c877ab042..0d7023486a2e1 100644
--- a/solution/0300-0399/0377.Combination Sum IV/Solution.java	
+++ b/solution/0300-0399/0377.Combination Sum IV/Solution.java	
@@ -1,27 +1,14 @@
 class Solution {
-        public int combinationSum4(int[] n, int target) {
+    public int combinationSum4(int[] nums, int target) {
         int[] dp = new int[target + 1];
-        Arrays.fill(dp, -1);
         dp[0] = 1;
-        return combinationSum4Dfs(n, dp, target);
-
-    }
-
-    private int combinationSum4Dfs(int[] n, int[] dp, int target) {
-        if (target < 0) {
-            return 0;
-        }
-
-        if (dp[target] != -1) {
-            return dp[target];
-        }
-
-        int rt = 0;
-        for (int v : n) {
-            rt += combinationSum4Dfs(n, dp, target - v);
+        for (int i = 1; i <= target; i++) {
+            for (int num : nums) {
+                if (i - num >= 0) {
+                    dp[i] += dp[i - num];
+                }
+            }
         }
-
-        dp[target] = rt;
         return dp[target];
     }
-}
\ No newline at end of file
+}
diff --git a/solution/0300-0399/0377.Combination Sum IV/Solution.py b/solution/0300-0399/0377.Combination Sum IV/Solution.py
new file mode 100644
index 0000000000000..48aba8d945d91
--- /dev/null
+++ b/solution/0300-0399/0377.Combination Sum IV/Solution.py	
@@ -0,0 +1,9 @@
+class Solution:
+    def combinationSum4(self, nums: List[int], target: int) -> int:
+        dp = [0 for i in range(target + 1)]
+        dp[0] = 1
+        for i in range(1, target + 1):
+            for num in nums:
+                if i - num >= 0:
+                    dp[i] += dp[i - num]
+        return dp[target]