Find Peak Element

Author: gavinfish

162 Find Peak Element.py

@@ -0,0 +1,33 @@
+'''
+A peak element is an element that is greater than its neighbors.
+
+Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.
+
+The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.
+
+You may imagine that num[-1] = num[n] = -∞.
+
+For example, in array [1, 2, 3, 1], 3 is a peak element and your function should return the index number 2.
+
+Note:
+Your solution should be in logarithmic complexity.
+'''
+
+class Solution(object):
+    def findPeakElement(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        left, right = 0, len(nums) - 1
+        while left < right:
+            mid = (right + left) // 2
+            if nums[mid] < nums[mid + 1]:
+                left = mid + 1
+            else:
+                right = mid
+        return left
+
+
+if __name__ == "__main__":
+    assert Solution().findPeakElement([1, 2, 3, 1]) == 2