src/bin/subarray-sum-equals-k.rs

Author: bestgopher

Diff for: src/bin/subarray-sum-equals-k.rs

@@ -0,0 +1,22 @@
+fn main() {
+    assert_eq!(39, Solution::subarray_sum(vec![0, 0, 0, 0, 1, -1, 0, 0, 1, 1, 0, 0, 2, -2, 2], 2));
+}
+
+struct Solution;
+
+impl Solution {
+    pub fn subarray_sum(nums: Vec<i32>, k: i32) -> i32 {
+        let mut sums = std::collections::HashMap::<i32, i32>::new();
+        sums.insert(0, 1);
+        let mut sum = 0;
+        let mut count = 0;
+        for &i in nums.iter() {
+            sum += i;
+            if let Some(s) = sums.get(&(sum - k)) {
+                count += *s
+            }
+            sums.entry(sum).and_modify(|x| *x += 1).or_insert(1);
+        }
+        count
+    }
+}