NewCodeTemplate

模板/树/LCA最近共同祖先.cpp

@@ -0,0 +1,51 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+struct TreeNode{
+    int val;
+    TreeNode* left;
+    TreeNode* right;
+
+    TreeNode(int _val): val(_val), left(nullptr), right(nullptr) {}
+};
+TreeNode* buildTree(const vector<int>& arr, int& idx){
+    if(arr.empty()) return nullptr;
+    if(idx >= arr.size() || arr[idx] == 0){
+        idx++;
+        return nullptr;
+    }
+
+    TreeNode* node = new TreeNode(arr[idx++]);
+    node->left = buildTree(arr, idx);
+    node->right = buildTree(arr, idx);
+
+    return node;
+}
+TreeNode* LCA = nullptr;
+TreeNode* check(TreeNode* root, int val1, int val2){
+    if(root == nullptr) return nullptr;
+    if(root->val == val1 || root->val == val2) return root;
+
+    TreeNode* lc = check(root->left, val1, val2);
+    TreeNode* rc = check(root->right, val1, val2);
+
+    if(lc && rc) return root;
+    return (lc ? lc : rc);
+
+}
+int main(){
+    //前序增强输入
+    int n;
+    cin >> n;
+    vector<int> arr(n);
+    for(int i = 0; i < n; i++){
+        cin >> arr[i];
+    }
+    int pa, pb;
+    cin >> pa >> pb;
+    int p = 0;
+    TreeNode* root = buildTree(arr, p);
+    LCA = check(root, pa, pb);
+    cout << LCA->val << endl;
+    return 0;
+}