Create: 1095-find-in-mountain-array.java

java/1095-find-in-mountain-array.java

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+/**
+ * // This is MountainArray's API interface.
+ * // You should not implement it, or speculate about its implementation
+ * interface MountainArray {
+ *     public int get(int index) {}
+ *     public int length() {}
+ * }
+ */
+
+class Solution {
+    public int findInMountainArray(int target, MountainArray mountainArr) {
+        int maxIndex = findMax(mountainArr);
+        int leftResult = binarySearchLeft(mountainArr, target, maxIndex);
+        int rightResult = binarySearchRight(mountainArr, target, maxIndex);
+
+        return (leftResult == -1 && rightResult == -1) ? -1 : leftResult == -1 ? rightResult : leftResult;
+    }
+
+    public int findMax(MountainArray array) {
+        int left = 0;
+        int right = array.length() - 1;
+
+        while (left<=right) {
+            int mid = left + (right - left)/2;
+            if (array.get(mid) < array.get(mid + 1)) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+
+        return left;
+    }
+
+    public int binarySearchLeft(MountainArray array, int target, int right) {
+        int left = 0;
+
+        while (left<=right) {
+            int mid = left + (right - left)/2;
+            int midValue = array.get(mid);
+            if (midValue < target) {
+                left = mid + 1;
+            } else if (midValue > target) {
+                right = mid - 1;
+            } else {
+                return mid;
+            }
+        }
+        return -1;
+    }
+
+    public int binarySearchRight(MountainArray array, int target, int left) {
+        int right = array.length() - 1;
+
+        while (left <= right) {
+            int mid = left + (right - left)/2;
+            int midValue = array.get(mid);
+
+            if (midValue < target) {
+                right = mid - 1;
+            } else if (midValue > target) {
+                left = mid + 1;
+            } else {
+                return mid;
+            }
+        }
+        return -1;
+    }
+}