Binary Search 2

FindFirstAndLast.java

@@ -0,0 +1,38 @@
+public class FindFirstAndLast {
+    public int[] searchRange(int[] nums, int target) {
+        int first = -1, last = -1, left = 0, right = nums.length - 1, mid;
+
+        // Search for the first occurrence of target
+        while (left <= right) {
+            mid = left + (right - left) / 2;
+
+            if (nums[mid] == target) {
+                first = mid;
+                right = mid - 1;
+            } else if (nums[mid] < target) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+
+        left = 0;
+        right = nums.length - 1;
+
+         // Search for the last occurrence of target
+        while (left <= right) {
+            mid = left + (right - left) / 2;
+
+            if (nums[mid] == target) {
+                last = mid;
+                left = mid + 1;
+            } else if (nums[mid] < target) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+
+        return new int[]{first, last};
+    }
+}

FindMin.java

@@ -0,0 +1,23 @@
+public class FindMin {
+    public int findMin(int[] nums) {
+        int left = 0, right = nums.length - 1, mid, min = Integer.MAX_VALUE;
+
+        while (left <= right) {
+            // check if sorted
+            if (nums[left] <= nums[right]) {
+                min = Math.min(min, nums[left]);
+                break;
+            }
+
+            mid = left + (right - left) / 2;
+            min = Math.min(min, nums[mid]);
+
+            if (nums[mid] >= nums[left]) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+        return min;
+    }
+}

FindPeak.java

@@ -0,0 +1,27 @@
+public class FindPeak {
+
+    public int findPeakElement(int[] nums) {
+        int left = 0, right = nums.length - 1, MID;
+        boolean leftCheck;
+        boolean rightCheck;
+
+        while (left <= right) {
+            MID = left + (right - left) / 2;
+            // check left side then check right side also
+            leftCheck = (MID == 0) || nums[MID] > nums[MID - 1];
+            rightCheck = (MID == nums.length - 1) || nums[MID] > nums[MID + 1];
+
+            if (leftCheck && rightCheck) {
+                return MID;
+            }
+
+            if (MID > 0 && nums[MID - 1] > nums[MID]) {
+                right = MID - 1;
+            } else {
+                left = MID + 1;
+            }
+        }
+
+        return -1;
+    }
+}