Added solution for Count Pairs Whose Sum is Less than Target

week5/count-pairs-whose-sum-is-less-than-target.py

@@ -0,0 +1,15 @@
+class Solution:
+    def countPairs(self, nums: List[int], target: int) -> int:
+        slow,fast=0,len(nums)-1
+        nums.sort()
+        count=0
+        while fast>slow :
+            if nums[slow] + nums[fast]< target:
+                count+=fast-slow
+                slow+=1
+            else:
+                fast-=1
+        return count
+
+
+