99 lines
2.3 KiB
Rust
99 lines
2.3 KiB
Rust
/**
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* [685] Redundant Connection II
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*/
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pub struct Solution {}
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// submission codes start here
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struct UnionFindSet {
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parents: Vec<usize>,
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}
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impl UnionFindSet {
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fn new(n: usize) -> Self {
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Self {
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parents: (0..=n).collect(),
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}
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}
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fn find(&mut self, n: usize) -> usize {
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if self.parents[n] == n {
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n
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} else {
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self.parents[n] = self.find(self.parents[n]);
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self.parents[n]
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}
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}
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fn merge(&mut self, a: usize, b: usize) {
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let (a, b) = (self.find(a), self.find(b));
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self.parents[a] = b;
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}
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}
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impl Solution {
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pub fn find_redundant_directed_connection(edges: Vec<Vec<i32>>) -> Vec<i32> {
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let n = edges.len();
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let mut set = UnionFindSet::new(n + 1);
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let mut parents: Vec<usize> = (0..=n).collect();
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let (mut conflict, mut cycle) = (usize::MAX, usize::MAX);
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for (i, edge) in edges.iter().enumerate() {
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let (first, second) = (edge[0] as usize, edge[1] as usize);
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if parents[second] != second {
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// There are the parents for second
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conflict = i;
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} else {
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parents[second] = first;
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if set.find(first) == set.find(second) {
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// There are a cycle between first and second.
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cycle = i;
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} else {
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set.merge(first, second);
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}
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}
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}
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if conflict == usize::MAX {
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edges[cycle].clone()
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} else {
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let result = edges[conflict].clone();
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if cycle == usize::MAX {
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result
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} else {
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vec![parents[result[1] as usize] as i32, result[1]]
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}
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}
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_685() {
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assert_eq!(
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vec![2, 3],
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Solution::find_redundant_directed_connection(vec![vec![1, 2], vec![1, 3], vec![2, 3]])
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);
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assert_eq!(
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vec![4, 1],
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Solution::find_redundant_directed_connection(vec![
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vec![1, 2],
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vec![2, 3],
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vec![3, 4],
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vec![4, 1],
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vec![1, 5]
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])
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);
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}
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}
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