Find champion ii

Graph Theory

70.3% acceptance

Feb 25, 2026

595

There are n teams numbered from 0 to n - 1 in a tournament; each team is also a node in a DAG. You are given the integer n and a 0-indexed 2D integer array edges of length m representing the DAG, where edges[i] = [ui, vi] indicates that there is a directed edge from team ui to team vi in the graph. A directed edge from a to b means team a is stronger than team b. Team a will be the champion if there is no team b that is stronger than team a. Return the team that will be the champion if there is a unique champion, otherwise return -1.

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn find_champion(n: i32, edges: Vec<Vec<i32>>) -> i32 {
    let n = n as usize;
    let mut in_degree = vec![0usize; n];
    for e in &edges {
      in_degree[e[1] as usize] += 1;
    }
    let zeros: Vec<usize> = (0..n).filter(|&i| in_degree[i] == 0).collect();
    if zeros.len() == 1 { zeros[0] as i32 } else { -1 }
  }
}