Completed Binary Search 2

min-rsortedarray.cpp

@@ -0,0 +1,28 @@
+class Solution {
+public:
+    int findMin(vector<int>& nums) {
+        int n = nums.size();
+        int low = 0 ;
+        int high = nums.size() - 1;
+
+        while(low <=high){
+            if(nums[low]<= nums[high]) return nums[low];//only true when the array is sorted and not rotated
+
+            int mid = low + (high - low)/2;
+
+            if((mid == 0 || nums[mid] < nums[mid -1]) && (mid == n-1 || nums[mid] < nums[mid + 1])) return nums[mid];
+            //case 1: mid at 0th index
+            //case 2: mid at last index
+            //case 3: mid is somewhere in between and we are checking if neighbours are greater or not 
+
+            else if(nums[low] <= nums[mid]){
+                low = mid + 1;//minimum lies in right of mid
+            }
+            else{
+                high = mid - 1;//minimum lies in the left of mid
+            }
+        }
+
+        return -1;
+    }
+};

peakelement.cpp

@@ -0,0 +1,31 @@
+class Solution {
+public:
+    int findPeakElement(vector<int>& nums) {
+        int n = nums.size();
+        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])){
+                //case 1 : mid at 0th index and greater than the 1st index element
+                //case 2 : mid at the last index and greater than the penultimate index element
+                //case 3 : checking if the mid is greater than its neighbours or not
+                return mid;
+            }
+
+            else if(mid < n-1 && nums[mid] < nums[mid+1]){
+                // making sure mid doesnt go out of bounds
+                // here mid is less than mid + 1,hence we move to the right of mid
+                low = mid + 1;
+            }
+
+            else{ //if(nums[mid] > nums[mid+1])
+                high = mid - 1;
+            }
+        }
+
+        return -1;
+    }
+};