From 113944f5c9d8eeeddfe268561c9d20ffdb708bc5 Mon Sep 17 00:00:00 2001
From: GreyZeng <410486047@qq.com>
Date: Wed, 22 Nov 2023 15:14:59 +0800
Subject: [PATCH] update code

---
 ...AndLastPositionOfElementInSortedArray.java | 57 ++++++++++---------
 .../LeetCode_0162_FindPeakElement.java        | 42 ++++++++------
 2 files changed, 55 insertions(+), 44 deletions(-)

diff --git a/src/main/java/git/snippet/binarysearch/LeetCode_0034_FindFirstAndLastPositionOfElementInSortedArray.java b/src/main/java/git/snippet/binarysearch/LeetCode_0034_FindFirstAndLastPositionOfElementInSortedArray.java
index 3ee90a4b..f7e9a5a5 100644
--- a/src/main/java/git/snippet/binarysearch/LeetCode_0034_FindFirstAndLastPositionOfElementInSortedArray.java
+++ b/src/main/java/git/snippet/binarysearch/LeetCode_0034_FindFirstAndLastPositionOfElementInSortedArray.java
@@ -5,51 +5,52 @@ package git.snippet.binarysearch;
 // 如果数组中不存在目标值 target，返回[-1, -1]。
 // 你必须设计并实现时间复杂度为O(log n)的算法解决此问题。
 // https://www.cnblogs.com/greyzeng/p/16622554.html
+// https://www.lintcode.com/problem/1536/
 // https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/
 public class LeetCode_0034_FindFirstAndLastPositionOfElementInSortedArray {
     public int[] searchRange(int[] nums, int target) {
         return new int[]{left(nums, target), right(nums, target)};
     }
 
-    private int left(int[] nums, int target) {
-        if (nums == null || nums.length < 1) {
+    public int left(int[] nums, int target) {
+        if (nums == null || nums.length == 0) {
             return -1;
         }
-        int l = 0;
-        int r = nums.length - 1;
-        int ans = -1;
-        while (l <= r) {
-            int m = l + ((r - l) >> 1);
-            if (nums[m] == target) {
-                ans = m;
-                r = m - 1;
-            } else if (nums[m] > target) {
-                r = m - 1;
+        int left = 0;
+        int right = nums.length - 1;
+        int result = -1;
+        while (left <= right) {
+            int mid = left + ((right - left) >> 1);
+            if (nums[mid] == target) {
+                result = mid;
+                right = mid - 1;
+            } else if (nums[mid] < target) {
+                left = mid + 1;
             } else {
-                l = m + 1;
+                right = mid - 1;
             }
         }
-        return ans;
+        return result;
     }
 
-    private int right(int[] nums, int target) {
-        if (nums == null || nums.length < 1) {
+    public int right(int[] nums, int target) {
+        if (nums == null || nums.length == 0) {
             return -1;
         }
-        int l = 0;
-        int r = nums.length - 1;
-        int ans = -1;
-        while (l <= r) {
-            int m = l + ((r - l) >> 1);
-            if (nums[m] == target) {
-                ans = m;
-                l = m + 1;
-            } else if (nums[m] < target) {
-                l = m + 1;
+        int left = 0;
+        int right = nums.length - 1;
+        int result = -1;
+        while (left <= right) {
+            int mid = left + ((right - left) >> 1);
+            if (nums[mid] == target) {
+                result = mid;
+                left = mid + 1;
+            } else if (nums[mid] < target) {
+                left = mid + 1;
             } else {
-                r = m - 1;
+                right = mid - 1;
             }
         }
-        return ans;
+        return result;
     }
 }
diff --git a/src/main/java/git/snippet/binarysearch/LeetCode_0162_FindPeakElement.java b/src/main/java/git/snippet/binarysearch/LeetCode_0162_FindPeakElement.java
index 0ed28784..48ee10d5 100644
--- a/src/main/java/git/snippet/binarysearch/LeetCode_0162_FindPeakElement.java
+++ b/src/main/java/git/snippet/binarysearch/LeetCode_0162_FindPeakElement.java
@@ -13,29 +13,39 @@ package git.snippet.binarysearch;
 // 笔记：https://www.cnblogs.com/greyzeng/p/16622554.html
 public class LeetCode_0162_FindPeakElement {
     public int findPeakElement(int[] nums) {
+        // 处理 nums <= 2 的情况
         if (nums.length == 1) {
             return 0;
         }
         if (nums.length == 2) {
             return nums[0] > nums[1] ? 0 : 1;
         }
-        int l = 0;
-        int r = nums.length - 1;
-        while (l <= r) {
-            if (nums[l] > nums[l + 1]) {
-                return l;
-            }
-            if (nums[r] > nums[r - 1]) {
-                return r;
-            }
-            int m = l + ((r - l) >> 1);
-            if (nums[m] > nums[m - 1] && nums[m] > nums[m + 1]) {
-                return m;
-            } else if (nums[m] < nums[m - 1]) {
-                r = m - 1;
+        int left = 0;
+        int right = nums.length - 1;
+        if (nums[left] > nums[left + 1]) {
+            return left;
+        } else {
+            left = left + 1;
+        }
+        if (nums[right] > nums[right - 1]) {
+            return right;
+        } else {
+            right = right - 1;
+        }
+        if (left == right) {
+            return left;
+        }
+        while (left <= right) {
+            int mid = left + ((right - left) >> 1);
+            if (nums[mid] > nums[mid + 1] && nums[mid] > nums[mid - 1]) {
+                return mid;
+            } else if (nums[mid] > nums[mid + 1]) {
+                right = mid - 1;
+            } else if (nums[mid] > nums[mid - 1]) {
+                left = mid + 1;
             } else {
-                // nums[m] < nums[m + 1]
-                l = m + 1;
+                // nums[mid] < nums[mid - 1] && nums[mid] < nums[mid + 1]
+                left = mid + 1;
             }
         }
         return -1;
-- 
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