Create 1498-number-of-subsequences-that-satisfy-the-given-sum-condition.kt

Author: a93a

kotlin/1498-number-of-subsequences-that-satisfy-the-given-sum-condition.kt

@@ -0,0 +1,25 @@
+class Solution {
+    fun numSubseq(nums: IntArray, target: Int): Int {
+        nums.sort()
+        val mod = 1000000000 + 7
+
+        val pow = IntArray(nums.size)
+        pow[0] = 1
+        for (i in 0 until nums.size - 1)
+            pow[i + 1] = pow[i] * 2 % mod
+
+        var left = 0
+        var right = nums.lastIndex
+        var res = 0
+        while (left <= right) {
+            if (nums[left] + nums[right] > target) {
+                right--
+            } else {
+                res = (res + pow[right - left]) % mod
+                left++
+            }
+        }
+
+        return res
+    }
+}