leetcode: Add cpp impl to 0496

src/leetcode/0496.next-greater-element-i/.gitignore

@@ -0,0 +1 @@
+/main

src/leetcode/0496.next-greater-element-i/Makefile

@@ -0,0 +1,3 @@
+
+build: main.cpp
+	g++ -g main.cpp -o main

src/leetcode/0496.next-greater-element-i/index.md

@@ -34,4 +34,10 @@
 ```rust
 {{#include src/main.rs:5:6}}
 {{#include src/main.rs:40:70}}
+```
+
+C++ 实现如下:
+
+```cpp
+{{#include main.cpp:5:}}
 ```

src/leetcode/0496.next-greater-element-i/main.cpp

@@ -0,0 +1,77 @@
+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#include <cassert>
+#include <climits>
+
+#include <iostream>
+#include <stack>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+std::vector<int> nextGreaterElement(std::vector<int>& nums1, std::vector<int>& nums2) {
+  std::stack<int> monotonic_stack;
+  std::unordered_map<int, int> map;
+  int max_num = INT_MAX;
+
+  // 构造递增式单调栈
+  for (int num2 : nums2) {
+    if (num2 < max_num) {
+      // 将较小的元素入栈
+      max_num = num2;
+      monotonic_stack.push(num2);
+    } else {
+      // 将较小的元素出栈
+      while (!monotonic_stack.empty() && monotonic_stack.top() < num2) {
+        const int top = monotonic_stack.top();
+        monotonic_stack.pop();
+        map.emplace(top, num2);
+      }
+      // 将当前元素入栈
+      monotonic_stack.push(num2);
+    }
+  }
+
+  std::vector<int> out;
+  for (int num1 : nums1) {
+    auto iter = map.find(num1);
+    if (iter == map.cend()) {
+      out.push_back(-1);
+    } else {
+      out.push_back(iter->second);
+    }
+  }
+
+  return out;
+}
+
+void checkSolution() {
+  {
+    std::vector<int> nums1 = {4, 1, 2};
+    std::vector<int> nums2 = {1, 3, 4, 2};
+    std::vector<int> expected = {-1, 3, -1};
+    assert(nextGreaterElement(nums1, nums2) == expected);
+  }
+
+  {
+    std::vector<int> nums1 = {2, 4};
+    std::vector<int> nums2 = {1, 2, 3, 4};
+    std::vector<int> expected = {3, -1};
+    assert(nextGreaterElement(nums1, nums2) == expected);
+  }
+
+  {
+    std::vector<int> nums1 = {1, 3, 5, 2, 4};
+    std::vector<int> nums2 = {6, 5, 4, 3, 2, 1, 7};
+    std::vector<int> expected = {7, 7, 7, 7, 7};
+    assert(nextGreaterElement(nums1, nums2) == expected);
+  }
+}
+
+int main() {
+  checkSolution();
+
+  return 0;
+}