update 852 java

Author: yennanliu

.github/workflows/pythonapp.yml

@@ -1,36 +1,36 @@
-name: Python application
+# name: Python application
 
-on: [push]
+# on: [push]
 
-jobs:
-  build:
+# jobs:
+#   build:
 
-    runs-on: ubuntu-latest
+#     runs-on: ubuntu-latest
 
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python 3.10.15
-      uses: actions/setup-python@v1
-      with:
-        python-version: 3.10.15
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        #pip install -r requirements.txt
-    - name: Lint with flake8
-      run: |
-        pip install flake8
-        # stop the build if there are Python syntax errors or undefined names
-        #flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        #flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
-    - name: Run pytest
-      run: |
-        pip install pytest
-        python script/get_review_list.py        
-    - name: List LC
-      run: |
-        pip install pytest
-        #pytest
-        bash script/list_leetcode_solutions_by_type.sh
-        bash script/get_company_LC.sh google output1.txt
+#     steps:
+#     - uses: actions/checkout@v2
+#     - name: Set up Python 3.10.15
+#       uses: actions/setup-python@v1
+#       with:
+#         python-version: 3.10.16
+#     - name: Install dependencies
+#       run: |
+#         python -m pip install --upgrade pip
+#         #pip install -r requirements.txt
+#     - name: Lint with flake8
+#       run: |
+#         pip install flake8
+#         # stop the build if there are Python syntax errors or undefined names
+#         #flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+#         # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
+#         #flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+#     - name: Run pytest
+#       run: |
+#         pip install pytest
+#         python script/get_review_list.py        
+#     - name: List LC
+#       run: |
+#         pip install pytest
+#         #pytest
+#         bash script/list_leetcode_solutions_by_type.sh
+#         bash script/get_company_LC.sh google output1.txt

leetcode_java/src/main/java/LeetCodeJava/BinarySearch/PeakIndexInAMountainArray.java

@@ -136,7 +136,66 @@ else if (arr[mid] < arr[mid + 1]) {
         // mountain array)
     }
 
-    // V1
+    // V1-1
+    // https://leetcode.com/problems/peak-index-in-a-mountain-array/editorial/
+    // IDEA : LINEAR SCAN
+    public int peakIndexInMountainArray_1_1(int[] arr) {
+        int i = 0;
+        while (arr[i] < arr[i + 1]) {
+            i++;
+        }
+        return i;
+    }
+
+    // V1-2
+    // https://leetcode.com/problems/peak-index-in-a-mountain-array/editorial/
+    // IDEA : Binary Search
+    public int peakIndexInMountainArray_1_2(int[] arr) {
+        int l = 0, r = arr.length - 1, mid;
+        while (l < r) {
+            mid = (l + r) / 2;
+            if (arr[mid] < arr[mid + 1])
+                l = mid + 1;
+            else
+                r = mid;
+        }
+        return l;
+    }
 
     // V2
+    // https://leetcode.com/problems/peak-index-in-a-mountain-array/solutions/6237785/binary-search-by-retr0sec-si97/
+    // IDEA: BINARY SEARCH
+    public int peakIndexInMountainArray_2(int[] arr) {
+
+        int left = 0;
+        int right = arr.length - 1;
+
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+            if (mid >= 1 && mid <= arr.length - 1 && arr[mid] < arr[mid - 1]) {
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return right;
+    }
+
+    // V3
+    // https://leetcode.com/problems/peak-index-in-a-mountain-array/solutions/6235886/check-out-this-solution-if-you-want-most-si4s/
+    // IDEA: BINARY SEARCH
+    public int peakIndexInMountainArray(int[] arr) {
+        int start = 0;
+        int end = arr.length - 1;
+        while (start != end) {
+            int mid = start + (end - start) / 2;
+            if (arr[mid] < arr[mid + 1]) {
+                start = mid + 1;
+            } else if (arr[mid] > arr[mid + 1]) {
+                end = mid;
+            }
+        }
+        return start;
+    }
+
 }