Create number-of-subsequences-that-satisfy-the-given-sum-condition.py

Author: kamyu104

Python/number-of-subsequences-that-satisfy-the-given-sum-condition.py

@@ -0,0 +1,21 @@
+# Time:  O(nlogn)
+# Space: O(n)
+
+class Solution(object):
+    def numSubseq(self, nums, target):
+        """
+        :type nums: List[int]
+        :type target: int
+        :rtype: int
+        """
+        MOD = 10**9 + 7
+        nums.sort()
+        result = 0
+        left, right = 0, len(nums)-1
+        while left <= right:
+            if nums[left]+nums[right] > target:
+                right -= 1
+            else:
+                result = (result+pow(2, right-left, MOD))%MOD
+                left += 1
+        return result