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Author: karlosye

0153-find-minimum-in-rotated-sorted-array/0153-find-minimum-in-rotated-sorted-array.java

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+// find the min. number in rotated sorted array; all the numbers are unique in the array; there are at least 1 item in the array
+
+// approach: binary search - left&right pointer; use 2-pointers technique to find the sorted portion and return the leftmost value (min.value)
+
+class Solution {
+    public int findMin(int[] nums) {
+        
+        // init left/right pointer
+        int left = 0;
+        int right = nums.length - 1;
+        
+        int res = nums[0];
+        
+        while (left <= right) {
+            
+            // if this portion is already sorted:
+            if (nums[left] < nums[right]) {
+                
+                res = Math.min(res, nums[left]);
+                break;
+            }
+            
+            // if this portion is not sorted: take the midpoint and contunue the binary search:
+            int mid = (left + right)/2;
+            res = Math.min(res, nums[mid]);
+            
+            // adjust the left/right pointer
+            if (nums[mid] >= nums[left]) {
+                left = mid+1;
+            } else {
+                right = mid-1;
+            }
+        }
+        
+        return res;
+    }
+}