Done Binary Search 2

FirstAndLastInSortedArray.java

@@ -0,0 +1,57 @@
+// Time Complexity :O(logn)
+// Space Complexity :O(1)
+// Did this code successfully run on Leetcode :Yes
+// Any problem you faced while coding this :
+class Solution {
+    public int[] searchRange(int[] nums, int target) {
+        int n = nums.length;
+        int low = 0;
+        int high = n - 1;
+        if (nums == null || n == 0)
+            return new int[] { -1, -1 };
+        if (target < nums[0] || target > nums[n - 1])
+            return new int[] { -1, -1 };
+        int firstIndex = binarySearchFirst(nums, low, high, target);
+        if (firstIndex == -1)
+            return new int[] { -1, -1 };
+        int lastIndex = binarySearchLast(nums, firstIndex, high, target);
+        return new int[] { firstIndex, lastIndex };
+    }
+
+    private int binarySearchFirst(int[] nums, int low, int high, int target) {
+        while (low <= high) {
+            int mid = low + (high - low) / 2;
+            if (nums[mid] == target) {
+                if (mid == 0 || nums[mid] != nums[mid - 1]) {
+                    return mid;
+                } else {
+                    high = mid - 1;
+                }
+            } else if (nums[mid] > target) {
+                high = mid - 1;
+
+            } else {
+                low = mid + 1;
+            }
+        }
+        return -1;
+    }
+
+    private int binarySearchLast(int[] nums, int low, int high, int target) {
+        while (low <= high) {
+            int mid = low + (high - low) / 2;
+            if (nums[mid] == target) {
+                if (mid == high || nums[mid] != nums[mid + 1]) {
+                    return mid;
+                } else {
+                    low = mid + 1;
+                }
+            } else if (nums[mid] < target) {
+                low = mid + 1;
+            } else {
+                high = mid - 1;
+            }
+        }
+        return -1;
+    }
+}

MinInRotatedSortedArray.java

@@ -0,0 +1,26 @@
+// Time Complexity :O(logn)
+// Space Complexity :O(1)
+// Did this code successfully run on Leetcode :Yes
+// Any problem you faced while coding this :
+class Solution {
+    public int findMin(int[] nums) {
+        int n = nums.length;
+        int low = 0;
+        int high = nums.length - 1;
+        while (low <= high) {
+            int mid = low + (high - low) / 2;
+            if (nums[low] <= nums[high]) { // checking sorted array
+                return nums[low];
+            } else if ((mid == 0 || nums[mid] < nums[mid - 1]) && (nums[mid] < nums[mid + 1])) {
+                return nums[mid]; // checking left and right of mid to determine if mid is min;
+            } else if (nums[low] <= nums[mid]) { // move the search to unsorted range;
+
+                low = mid + 1;
+            } else {
+                high = mid - 1;
+            }
+
+        }
+        return 8585;
+    }
+}

PeakElement.java

@@ -0,0 +1,23 @@
+// Time Complexity :O(logn)
+// Space Complexity :O(1)
+// Did this code successfully run on Leetcode :Yes
+// Any problem you faced while coding this :
+class Solution {
+    public int findPeakElement(int[] nums) {
+        int n = nums.length;
+        int low = 0;
+        int high = n - 1;
+        while (low <= high) {
+            int mid = low + (high - low) / 2;
+            if ((mid == 0 || nums[mid] > nums[mid - 1]) && (mid == n - 1 || nums[mid] > nums[mid + 1])) {
+                return mid;
+            } else if (mid > 0 && nums[mid - 1] > nums[mid]) {
+                high = mid - 1;
+            } else {
+                low = mid + 1;
+            }
+
+        }
+        return 8585;
+    }
+}