From 0e5e657a6d5ba057e8dfa77019b25c5404fe9a9b Mon Sep 17 00:00:00 2001
From: 243wresfdxvc <gpan20020205@gmail.com>
Date: Tue, 10 May 2022 23:04:35 +0000
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200404.=E5=B7=A6=E5=8F=B6?=
 =?UTF-8?q?=E5=AD=90=E4=B9=8B=E5=92=8C.md=20C=E8=AF=AD=E8=A8=80=E8=A7=A3?=
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---
 problems/0404.左叶子之和.md | 49 ++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md
index 6420da81..d7fd629e 100644
--- a/problems/0404.左叶子之和.md
+++ b/problems/0404.左叶子之和.md
@@ -466,6 +466,55 @@ func sumOfLeftLeaves(_ root: TreeNode?) -> Int {
 }
 ```
 
+## C
+递归法：
+```c
+int sumOfLeftLeaves(struct TreeNode* root){
+    // 递归结束条件：若当前结点为空，返回0
+    if(!root)
+        return 0;
+    
+    // 递归取左子树的左结点和和右子树的左结点和
+    int leftValue = sumOfLeftLeaves(root->left);
+    int rightValue = sumOfLeftLeaves(root->right);
+
+    // 若当前结点的左结点存在，且其为叶子结点。取它的值
+    int midValue = 0;
+    if(root->left && (!root->left->left && !root->left->right))
+        midValue = root->left->val;
+    
+    return leftValue + rightValue + midValue;
+}
+```
+
+迭代法:
+```c
+int sumOfLeftLeaves(struct TreeNode* root){
+    struct TreeNode* stack[1000];
+    int stackTop = 0;
+
+    // 若传入root结点不为空，将其入栈
+    if(root)
+        stack[stackTop++] = root;
+    
+    int sum = 0;
+    //若栈不为空，进行循环
+    while(stackTop) {
+        // 出栈栈顶元素
+        struct TreeNode *topNode = stack[--stackTop];
+        // 若栈顶元素的左孩子为左叶子结点，将其值加入sum中
+        if(topNode->left && (!topNode->left->left && !topNode->left->right))
+            sum += topNode->left->val;
+        
+        // 若当前栈顶结点有左右孩子。将他们加入栈中进行遍历
+        if(topNode->right)
+            stack[stackTop++] = topNode->right;
+        if(topNode->left)
+            stack[stackTop++] = topNode->left;
+    }
+    return sum;
+}
+```
 
 
 -----------------------