From 209dcdabf4fbc92b22be4103628c61bd24223508 Mon Sep 17 00:00:00 2001
From: SKTT1Ryze <ccc@neos.moe>
Date: Thu, 7 Mar 2024 18:36:01 +0800
Subject: [PATCH 1/2] add find peak element

---
 leetcode-cc/FindPeakElement.hpp | 26 ++++++++++++++++++++++++++
 runtime-cc/src/registration.cc  |  6 ++++++
 2 files changed, 32 insertions(+)
 create mode 100644 leetcode-cc/FindPeakElement.hpp

diff --git a/leetcode-cc/FindPeakElement.hpp b/leetcode-cc/FindPeakElement.hpp
new file mode 100644
index 0000000..2e71ccd
--- /dev/null
+++ b/leetcode-cc/FindPeakElement.hpp
@@ -0,0 +1,26 @@
+#include "TestHelper.h"
+#include "problem.h"
+#include "solution.h"
+
+using namespace std;
+
+IMPLEMENT_PROBLEM_CLASS(PFindPeakElement, 162, DIFFI_MEDIUM, TOPIC_ALGORITHMS,
+                        "Find Peak Element", "", {""});
+
+class SFindPeakElement : public ISolution {
+ public:
+  size_t problemId() const override { return 162; }
+  string name() const override {
+    return ("Solution for " + string("Find Peak Element"));
+  }
+  string location() const override { return __FILE_NAME__; }
+  int test() const override {
+    return testHelper<vector<int>, int>(
+        {{1, 2, 3, 1}, {1, 2, 1, 3, 5, 6, 4}}, {2, 5},
+        [this](auto input) { return this->findPeakElement(input); });
+  };
+  int benchmark() const override { return 0; }
+
+ private:
+  int findPeakElement(vector<int>& nums) const {}
+};
diff --git a/runtime-cc/src/registration.cc b/runtime-cc/src/registration.cc
index 1592fca..910a49d 100644
--- a/runtime-cc/src/registration.cc
+++ b/runtime-cc/src/registration.cc
@@ -23,6 +23,7 @@
 #include "../leetcode-cc/EvaluateReversePolishNotation.hpp"
 #include "../leetcode-cc/FindMinInRotatedSortedArray.hpp"
 #include "../leetcode-cc/FindMinInRotatedSortedArrayII.hpp"
+#include "../leetcode-cc/FindPeakElement.hpp"
 #include "../leetcode-cc/FindPlayersWithZeroOrOneLosses.hpp"
 #include "../leetcode-cc/FlattenBTreeToLinkedList.hpp"
 #include "../leetcode-cc/FourSum.hpp"
@@ -693,5 +694,10 @@ const int registerAll(std::shared_ptr<Container> handle) {
   handle->registerSolution(
       []() -> ArcSolution { return std::make_shared<SIntersectionOfTwoLL>(); });
 
+  handle->registerProblem(
+      []() -> ArcProblem { return std::make_shared<PFindPeakElement>(); });
+  handle->registerSolution(
+      []() -> ArcSolution { return std::make_shared<SFindPeakElement>(); });
+
   return 0;
 }

From 2a235c3a2af6e8329f796b52362248eaac9e3f0d Mon Sep 17 00:00:00 2001
From: SKTT1Ryze <ccc@neos.moe>
Date: Thu, 7 Mar 2024 18:52:17 +0800
Subject: [PATCH 2/2] impl find peak element

---
 leetcode-cc/FindPeakElement.hpp | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/leetcode-cc/FindPeakElement.hpp b/leetcode-cc/FindPeakElement.hpp
index 2e71ccd..ea638e8 100644
--- a/leetcode-cc/FindPeakElement.hpp
+++ b/leetcode-cc/FindPeakElement.hpp
@@ -1,3 +1,5 @@
+#include <algorithm>
+
 #include "TestHelper.h"
 #include "problem.h"
 #include "solution.h"
@@ -16,11 +18,37 @@ class SFindPeakElement : public ISolution {
   string location() const override { return __FILE_NAME__; }
   int test() const override {
     return testHelper<vector<int>, int>(
-        {{1, 2, 3, 1}, {1, 2, 1, 3, 5, 6, 4}}, {2, 5},
+        {{1, 2, 3, 1}, {1, 2, 1, 3, 5, 6, 4}}, {2, 1},
         [this](auto input) { return this->findPeakElement(input); });
   };
   int benchmark() const override { return 0; }
 
  private:
-  int findPeakElement(vector<int>& nums) const {}
+  int findPeakElement(vector<int>& nums) const {
+    int n = nums.size();
+    if (n == 1) return 0;
+    if (n == 2) return nums[0] < nums[1] ? 1 : 0;
+
+    if (nums[0] > nums[1]) {
+      return 0;
+    }
+
+    int prev = 0;
+    int current = 1;
+    int next = 2;
+
+    while (next <= n) {
+      if (next == n) {
+        return nums[prev] < nums[current] ? current : prev;
+      } else if (nums[prev] < nums[current] && nums[next] < nums[current]) {
+        return current;
+      } else {
+        prev++;
+        current++;
+        next++;
+      }
+    }
+
+    return -1;
+  }
 };