Map sum pairs

Hash Table String Design Trie

57.1% acceptance

Feb 20, 2026

1732

166

MapSum: insert key-value pairs, sum returns total value of keys with the given prefix.

Solution

Rust

Time O(2^n)

Space O(n)

LeetCode

solution.rs

use std::collections::HashMap;
struct MapSum {
  map: HashMap<String, i32>,
}

impl MapSum {
  fn new() -> Self {
    MapSum { map: HashMap::new() }
  }

  fn insert(&mut self, key: String, val: i32) {
    self.map.insert(key, val);
  }

  fn sum(&self, prefix: String) -> i32 {
    self.map.iter()
      .filter(|(k, _)| k.starts_with(&prefix))
      .map(|(_, &v)| v)
      .sum()
  }
}