Add problem 1498: Number of Subsequences That Satisfy the Given Sum C…

…ondition

src/lib.rs

@@ -568,6 +568,7 @@ pub mod problem_1476_subrectangle_queries;
 pub mod problem_1481_least_number_of_unique_integers_after_k_removals;
 pub mod problem_1486_xor_operation_in_an_array;
 pub mod problem_1487_making_file_names_unique;
+pub mod problem_1498_number_of_subsequences_that_satisfy_the_given_sum_condition;
 pub mod problem_1507_reformat_date;
 pub mod problem_1508_range_sum_of_sorted_subarray_sums;
 pub mod problem_1524_number_of_sub_arrays_with_odd_sum;

src/problem_1498_number_of_subsequences_that_satisfy_the_given_sum_condition/mod.rs

@@ -0,0 +1,23 @@
+pub mod two_pointer_and_math;
+
+pub trait Solution {
+    fn num_subseq(nums: Vec<i32>, target: i32) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            ((&[3, 5, 6, 7] as &[_], 9), 4),
+            ((&[3, 3, 6, 8], 10), 6),
+            ((&[2, 3, 3, 4, 6, 7], 12), 61),
+            ((&[5, 2, 4, 1, 7, 6, 8], 16), 127),
+        ];
+
+        for ((nums, target), expected) in test_cases {
+            assert_eq!(S::num_subseq(nums.to_vec(), target), expected);
+        }
+    }
+}

src/problem_1498_number_of_subsequences_that_satisfy_the_given_sum_condition/two_pointer_and_math.rs

@@ -0,0 +1,45 @@
+pub struct Solution;
+
+impl Solution {
+    pub fn num_subseq(nums: Vec<i32>, target: i32) -> i32 {
+        let modulo = 1_000_000_007;
+
+        let mut result = 0;
+        let mut nums = nums;
+        nums.sort_unstable();
+
+        let mut pow2 = vec![1; nums.len()];
+        for i in 1..nums.len() {
+            pow2[i] = (pow2[i - 1] * 2) % modulo;
+        }
+
+        let (mut left, mut right) = (0, nums.len() - 1);
+        while left <= right {
+            if nums[left] + nums[right] <= target {
+                result = (result + pow2[right - left]) % modulo;
+                left += 1;
+            } else {
+                if right == 0 {
+                    break;
+                };
+                right -= 1;
+            }
+        }
+
+        result
+    }
+}
+
+impl super::Solution for Solution {
+    fn num_subseq(nums: Vec<i32>, target: i32) -> i32 {
+        Self::num_subseq(nums, target)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}