From ce8309d2cd1c5159d2a93719c6c3c3ff93ae39e2 Mon Sep 17 00:00:00 2001
From: colorbox <colorbox222@gmail.com>
Date: Tue, 11 Feb 2025 01:39:37 +0900
Subject: [PATCH] 112. Path Sum

---
 112/step1.cpp | 21 +++++++++++++++++++++
 112/step2.cpp | 26 ++++++++++++++++++++++++++
 112/step3.cpp | 12 ++++++++++++
 3 files changed, 59 insertions(+)
 create mode 100644 112/step1.cpp
 create mode 100644 112/step2.cpp
 create mode 100644 112/step3.cpp

diff --git a/112/step1.cpp b/112/step1.cpp
new file mode 100644
index 0000000..0c292be
--- /dev/null
+++ b/112/step1.cpp
@@ -0,0 +1,21 @@
+/*
+Solve Time : 03:57
+
+Time : O(N)
+Space : O(N)
+
+再帰でざっくりと実装、特に悩むことなく実装完了
+*/
+class Solution {
+public:
+  bool hasPathSum(TreeNode* root, int target_sum) {
+    if (!root) {
+      return false;
+    }
+    if (!root->left && !root->right) {
+      return target_sum == root->val;
+    }
+    return hasPathSum(root->left, target_sum - root->val) || hasPathSum(root->right, target_sum - root->val);
+  }
+};
+
diff --git a/112/step2.cpp b/112/step2.cpp
new file mode 100644
index 0000000..7c0c461
--- /dev/null
+++ b/112/step2.cpp
@@ -0,0 +1,26 @@
+/*
+Time : O(N)
+Space : O(N)
+
+再帰ではなく、stackを使って実装
+*/
+class Solution {
+public:
+  bool hasPathSum(TreeNode* root, int target_sum) {
+    stack<pair<TreeNode*, int>> nodes_and_sums;
+    nodes_and_sums.emplace(root, target_sum);
+    while (!nodes_and_sums.empty()) {
+      auto [node, sum] = nodes_and_sums.top();
+      nodes_and_sums.pop();
+      if (!node) {
+        continue;
+      }
+      if (!node->left && !node->right && sum == node->val) {
+        return true;
+      }
+      nodes_and_sums.emplace(node->left, sum - node->val);
+      nodes_and_sums.emplace(node->right, sum - node->val);
+    }
+    return false;
+  }
+};
diff --git a/112/step3.cpp b/112/step3.cpp
new file mode 100644
index 0000000..26cba5d
--- /dev/null
+++ b/112/step3.cpp
@@ -0,0 +1,12 @@
+class Solution {
+public:
+  bool hasPathSum(TreeNode* root, int target_sum) {
+    if (!root) {
+      return false;
+    }
+    if (!root->left && !root->right) {
+      return target_sum == root->val;
+    }
+    return hasPathSum(root->left, target_sum - root->val) || hasPathSum(root->right, target_sum - root->val);
+  }
+};