process-tasks-using-servers.rs

// Process Tasks Using Servers
impl Solution {
    pub fn assign_tasks(servers: Vec<i32>, tasks: Vec<i32>) -> Vec<i32> {
        use std::cmp::Reverse;
        use std::collections::BinaryHeap;
        let n = servers.len();
        let mut ans = vec![0; tasks.len()];
        let mut free: BinaryHeap<Reverse<(i32, i32)>> = BinaryHeap::new();
        let mut busy: BinaryHeap<Reverse<(i32, i32)>> = BinaryHeap::new();
        let mut tick = 0;
        for i in 0..n {
            free.push(Reverse((servers[i], i as i32)));
        }
        for i in 0..tasks.len() {
            if free.is_empty() { tick = (busy.peek().unwrap().0).0; }
            else { tick = tick.max(i as i32); }
            while let Some(Reverse(top)) = busy.peek() {
                if top.0 != tick { break; }
                free.push(Reverse((servers[top.1 as usize], top.1)));
                busy.pop();
            }
            let u = (free.pop().unwrap().0).1;
            ans[i] = u;
            busy.push(Reverse((tick+tasks[i], u)));
        }
        ans
    }
}