LeetCode 767. Reorganize String

Problem Statement

use std::collections::{BinaryHeap, HashMap};

impl Solution {
    pub fn reorganize_string(s: String) -> String {
        let mut map: HashMap<char, i32> = HashMap::new();
        let mut heap: BinaryHeap<(i32, char)> = BinaryHeap::new();
        for c in s.chars() {
            let count = map.entry(c).or_insert(0);
            *count += 1;
        }
        let mut ans = "".to_string();
        for (k, v) in &map {
            if *v > ((s.len() + 1) / 2) as i32 {
                return ans;
            }
            heap.push((*v, *k));
        }
        while heap.len() >= 2 {
            let (mut t1, mut t2) = (heap.pop().unwrap(), heap.pop().unwrap());
            ans.push(t1.1); ans.push(t2.1);
            t1.0 -= 1; t2.0 -= 1;
            if t1.0 != 0 {
                heap.push(t1);
            }
            if t2.0 != 0 {
                heap.push(t2);
            }
        }

        if !heap.is_empty() {
            let t = heap.pop().unwrap();
            ans.push(t.1);
        }
        return ans;
    }
}