p2924

Author: ian-hon

src/p2924.rs

@@ -0,0 +1,61 @@
+use std::collections::{HashMap, HashSet};
+
+pub fn run() {
+    for i in [
+        (3, vec![vec![0,1],vec![1,2]]),
+        (4, vec![vec![0,2],vec![1,3],vec![1,2]])
+    ] {
+        println!("{}", find_champion(i.0, i.1));
+    }
+}
+
+pub fn find_champion(n: i32, edges: Vec<Vec<i32>>) -> i32 {
+    let mut parents: Vec<i32> = (0..n).collect();
+
+    for i in edges {
+        parents[i[1] as usize] = -1;
+        // has_parents.remove(&i[1]);
+    }
+
+    let mut last = 0;
+    let mut count = 0;
+    for i in parents {
+        if i == -1 {
+            continue;
+        }
+        if count != 0 {
+            return -1;
+        }
+        last = i;
+        count += 1;
+    }
+    if count == 1 {
+        return last;
+    }
+    -1
+
+
+    // let mut parents: HashMap<i32, Vec<i32>> = HashMap::new();
+
+    // for i in 0..n {
+    //     parents.insert(i, vec![]);
+    // }
+
+    // for i in edges {
+    //     parents.get_mut(&i[1]).unwrap().push(i[0]);
+    // }
+
+    // let mut candidates: Vec<i32> = vec![];
+    // for i in parents {
+    //     if !i.1.is_empty() {
+    //         continue;
+    //     }
+    //     candidates.push(i.0);
+    // }
+
+    // if candidates.len() != 1 {
+    //     return -1;
+    // }
+
+    // candidates[0]
+}