From 1775c33c9fcd5e0498948479072cbbe82843ade2 Mon Sep 17 00:00:00 2001
From: Sainnhe Park <i@sainnhe.dev>
Date: Fri, 16 Dec 2022 16:12:04 +0800
Subject: [PATCH] s0503

---
 include/s0503_next_greater_element_ii.hpp | 14 +++++++++
 notes/src/stack_and_queue.md              | 10 +++++++
 src/s0503_next_greater_element_ii.cpp     | 36 +++++++++++++++++++++++
 tests/s0503_next_greater_element_ii.cpp   | 17 +++++++++++
 4 files changed, 77 insertions(+)
 create mode 100644 include/s0503_next_greater_element_ii.hpp
 create mode 100644 src/s0503_next_greater_element_ii.cpp
 create mode 100644 tests/s0503_next_greater_element_ii.cpp

diff --git a/include/s0503_next_greater_element_ii.hpp b/include/s0503_next_greater_element_ii.hpp
new file mode 100644
index 0000000..b079f8d
--- /dev/null
+++ b/include/s0503_next_greater_element_ii.hpp
@@ -0,0 +1,14 @@
+#ifndef S0503_NEXT_GREATER_ELEMENT_II_HPP
+#define S0503_NEXT_GREATER_ELEMENT_II_HPP
+
+#include <vector>
+#include <stack>
+
+using namespace std;
+
+class S0503 {
+ public:
+  vector<int> nextGreaterElements(vector<int>& nums);
+};
+
+#endif
diff --git a/notes/src/stack_and_queue.md b/notes/src/stack_and_queue.md
index 4517090..d565317 100644
--- a/notes/src/stack_and_queue.md
+++ b/notes/src/stack_and_queue.md
@@ -29,6 +29,16 @@
 
 [496. 下一个更大元素 I](https://leetcode.com/problems/next-greater-element-i/)
 
+[503. 下一个更大元素 II](https://leetcode.com/problems/next-greater-element-ii/)
+
+Tips: 循环数组的处理方法：
+
+```cpp
+for (int i{0}; i < 2 * len; ++i) {
+  nums[i % len] ...
+}
+```
+
 ## 队列
 
 使用场景：
diff --git a/src/s0503_next_greater_element_ii.cpp b/src/s0503_next_greater_element_ii.cpp
new file mode 100644
index 0000000..9afa0c7
--- /dev/null
+++ b/src/s0503_next_greater_element_ii.cpp
@@ -0,0 +1,36 @@
+#include "s0503_next_greater_element_ii.hpp"
+
+// 循环数组首先考虑到的方法就是将两个数组拼接到一起处理。
+// 我们将两个数组拼接到一起，然后用单调栈即可，但这样做有些浪费内存。
+// 另一种处理方式是这样遍历：
+// for (int i{0}; i < 2 * len; ++i) {
+//   nums[i % len] ...
+// }
+
+vector<int> S0503::nextGreaterElements(vector<int>& nums) {
+  int len = nums.size();
+  if (len == 0) {
+    return vector<int> {};
+  } else if (len == 1) {
+    return vector<int> {-1};
+  }
+  vector<int> ans(len, -1);
+  stack<int> s;
+  for (int i{0}; i < 2 * len; ++i) {
+    if (s.empty()) {
+      s.push(i);
+      continue;
+    }
+    while (nums[i % len] > nums[s.top() % len]) {
+      if (ans[s.top() % len] == -1) {
+        ans[s.top() % len] = nums[i % len];
+      }
+      s.pop();
+      if (s.empty()) {
+        break;
+      }
+    }
+    s.push(i);
+  }
+  return ans;
+}
diff --git a/tests/s0503_next_greater_element_ii.cpp b/tests/s0503_next_greater_element_ii.cpp
new file mode 100644
index 0000000..25b83ec
--- /dev/null
+++ b/tests/s0503_next_greater_element_ii.cpp
@@ -0,0 +1,17 @@
+#include "s0503_next_greater_element_ii.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(Problem503, Case1) {
+  vector<int> nums{1, 2, 1};
+  vector<int> expected{2, -1, 2};
+  S0503 solution;
+  EXPECT_EQ(solution.nextGreaterElements(nums), expected);
+}
+
+TEST(Problem503, Case2) {
+  vector<int> nums{1, 2, 3, 4, 3};
+  vector<int> expected{2, 3, 4, -1, 4};
+  S0503 solution;
+  EXPECT_EQ(solution.nextGreaterElements(nums), expected);
+}