55 lines
1.9 KiB
Rust
55 lines
1.9 KiB
Rust
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impl Solution {
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pub fn get_max_chain_len(from: &Vec<Vec<usize>>, memos: &mut Vec<i32>, start: usize) -> i32 {
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let memo_val = *memos.get(start).unwrap_or(&-1);
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if memo_val != -1 {
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return memo_val;
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}
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let max_len = from.get(start)
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.unwrap()
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.iter()
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.map(|&next| Solution::get_max_chain_len(from, memos, next))
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.max()
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.unwrap_or(0) + 1;
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memos[start] = max_len;
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max_len
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}
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#[inline]
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pub fn is_predecessor(word: &String, of_word: &String) -> bool {
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let mut skipped = false;
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let mut oi = of_word.bytes();
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of_word.len() == word.len() + 1 && word.bytes()
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.all(|chr| {
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if chr == oi.next().unwrap() { // Before extra character
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true
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} else if !skipped && chr == oi.next().unwrap() { // Extra character, skipped ensures this can only run once
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skipped = true;
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true
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} else {
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false
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}
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})
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}
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pub fn longest_str_chain(words: Vec<String>) -> i32 {
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let (mut from, mut to) = (vec![vec![]; words.len()], vec![true; words.len()]);
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for (idx1, w1) in words.iter().enumerate() {
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for (idx2, w2) in words.iter().enumerate() {
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if Solution::is_predecessor(w1, w2) {
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from[idx1].push(idx2);
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to[idx2] = false;
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}
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}
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}
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let mut memos = vec![-1; words.len()];
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to.into_iter()
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.enumerate()
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.filter_map(|(to, froms)| {
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if froms {
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Some(Solution::get_max_chain_len(&from, &mut memos, to))
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} else {
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None
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}
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})
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.max()
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.unwrap()
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}
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}
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