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use std::cmp; use std::cmp::Ordering; pub struct SuffixArray { n: usize, s: Vec<u8>, array: Vec<usize>, } fn compare_node(i: usize, j: usize, k: usize, rank: &Vec<i32>) -> Ordering { if rank[i] != rank[j] { rank[i].cmp(&rank[j]) } else { let ri = if i + k <= rank.len() { rank[i + k] } else { -1 }; let rj = if j + k <= rank.len() { rank[j + k] } else { -1 }; ri.cmp(&rj) } } impl SuffixArray { pub fn new(s: &Vec<u8>) -> SuffixArray { let n = s.len(); let mut rank = vec![0; n + 1]; let mut array = vec![0; n + 1]; for i in 0..(n + 1) { array[i] = i; rank[i] = if i < n { s[i] as i32 } else { -1 }; } let mut tmp = vec![0; n + 1]; let mut k = 1; while k <= n { array.sort_by(|a, b| compare_node(*a, *b, k, &rank)); tmp[array[0]] = 0; for i in 1..(n + 1) { tmp[array[i]] = tmp[array[i - 1]] + if compare_node(array[i - 1], array[i], k, &rank) == Ordering::Less { 1 } else { 0 } } for i in 0..(n + 1) { rank[i] = tmp[i]; } k *= 2; } SuffixArray { n: n, array: array, s: s.clone(), } } pub fn contains(&self, t: &Vec<u8>) -> bool { let b = self.lower_bound(t); if b >= self.array.len() { false } else { let start = self.array[b]; let end = cmp::min(t.len() + start, self.s.len()); let sub = &self.s[start..end]; sub.cmp(t) == Ordering::Equal } } fn binary_search<F>(&self, t: &Vec<u8>, f: F) -> usize where F: Fn(&[u8], &Vec<u8>) -> bool, { let (mut a, mut b) = (-1, self.n as i32 + 1); while b - a > 1 { let c = (a + b) / 2; let start = self.array[c as usize]; let end = cmp::min(start + t.len(), self.s.len()); let sub = &self.s[start..end]; if f(sub, t) { a = c; } else { b = c; } } b as usize } pub fn lower_bound(&self, t: &Vec<u8>) -> usize { let check_function = |sub: &[u8], s: &Vec<u8>| sub.cmp(s) == Ordering::Less; self.binary_search(t, check_function) } pub fn upper_bound(&self, t: &Vec<u8>) -> usize { let check_function = |sub: &[u8], s: &Vec<u8>| sub.cmp(s) != Ordering::Greater; self.binary_search(t, check_function) } } #[cfg(test)] mod test { use super::*; use data_structure::segment_tree::SegmentTree; use std; use test_helper::TestCaseProducer; #[test] fn small_test() { let string = "abcdeabcde".to_owned().bytes().collect(); let sa = SuffixArray::new(&string); assert_eq!(sa.lower_bound(&"a".to_owned().bytes().collect()), 1); assert_eq!(sa.upper_bound(&"a".to_owned().bytes().collect()), 3); assert!(sa.contains(&"abcde".to_owned().bytes().collect())); assert!(!sa.contains(&"abce".to_owned().bytes().collect())); } #[test] fn corner_case() { let string = "cba".to_owned().bytes().collect(); let sa = SuffixArray::new(&string); assert_eq!(sa.lower_bound(&"c".to_owned().bytes().collect()), 3); assert_eq!(sa.upper_bound(&"c".to_owned().bytes().collect()), 4); } #[test] fn jag2014summer_day4_f() { let mut input = TestCaseProducer::new_from_directory("./assets/jag2014summer-day4/F/in/"); let mut output = TestCaseProducer::new_from_directory("./assets/jag2014summer-day4/F/out/"); while !input.is_empty() { let s: Vec<u8> = input.next::<String>().bytes().collect(); let n = s.len(); let reverse_s = { let mut r = s.clone(); r.reverse(); r }; let sa = SuffixArray::new(&s); let reverse_sa = SuffixArray::new(&reverse_s); let mut rmq = SegmentTree::new(n + 1, std::i64::MAX, |a, b| cmp::min(a, b)); let mut reverse_rmq = SegmentTree::new(n + 1, std::i64::MAX, |a, b| cmp::min(a, b)); for i in 0..(n + 1) { rmq.update(i, sa.array[i] as i64); reverse_rmq.update(i, reverse_sa.array[i] as i64); } let m = input.next(); for _ in 0..m { let x = input.next::<String>().bytes().collect(); let y = { let mut y: Vec<u8> = input.next::<String>().bytes().collect(); y.reverse(); y }; if !sa.contains(&x) { assert_eq!(output.next::<String>(), "0"); continue; } let low = sa.lower_bound(&x); let up = sa.upper_bound(&x); if !reverse_sa.contains(&y) { assert_eq!(output.next::<String>(), "0"); continue; } let reverse_low = reverse_sa.lower_bound(&y); let reverse_up = reverse_sa.upper_bound(&y); if low >= up || reverse_low >= reverse_up { assert_eq!(output.next::<String>(), "0"); } let s = rmq.query(low, up) as usize; let t = n - reverse_rmq.query(reverse_low, reverse_up) as usize; if s + x.len() <= t && s <= t - y.len() { assert_eq!(output.next::<usize>(), t - s); } else { assert_eq!(output.next::<String>(), "0"); } } } } }