Array-3 completed

h_index_1.py

@@ -0,0 +1,10 @@
+class Solution:
+    def hIndex(self, citations: List[int]) -> int:
+        citations.sort()
+        n=len(citations)
+
+        for i in range(n):
+            diff=n-i
+            if diff<=citations[i]:
+                return diff
+        return 0

rotate_array_k.py

@@ -0,0 +1,23 @@
+
+class Solution:
+    def rotate(self, nums: List[int], k: int) -> None:
+        """
+        Do not return anything, modify nums in-place instead.
+        """
+        n=len(nums)
+        k=k%n
+
+        self.reverse(nums,0,n-1)
+        self.reverse(nums,0,k-1)
+        self.reverse(nums,k,n-1)
+
+    def reverse(self,nums,left,right):
+        while left<right:
+            self.swap(nums,left,right)
+            left+=1
+            right-=1
+
+    def swap(self,nums,i,j):
+        temp=nums[i]
+        nums[i]=nums[j]
+        nums[j]=temp

trapping_water.py

@@ -0,0 +1,21 @@
+class Solution:
+    def trap(self, height: List[int]) -> int:
+        n=len(height)
+        lw,l=0,0
+        rw,r=n-1,n-1
+        result=0
+
+        while l<=r:
+            if height[rw]>height[lw]:
+                if height[lw]>height[l]:
+                    result+=height[lw]-height[l]
+                else:
+                    lw=l
+                l+=1
+            else:
+                if height[rw]>height[r]:
+                    result+=height[rw]-height[r]
+                else:
+                    rw=r
+                r-=1
+        return result