use std::fmt; use std::io::{self, BufRead}; use std::time::Instant; struct Graph { size: usize, matrix: Vec>, } struct Cutset { cardinality: usize, vertices: Vec, graph: Graph, } impl Clone for Graph { fn clone(&self) -> Self { let mut matrix = vec![vec![0; self.size]; self.size]; for row in 0..self.size { for col in 0..self.size { matrix[row][col] = self.matrix[row][col]; } } return Graph { size: self.size, matrix, }; } } impl fmt::Display for Graph { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for row in 0..self.size { for col in 0..self.size { write!(f, "{}", self.matrix[row][col])?; if col < self.size - 1 { write!(f, " ")?; } } if row < self.size - 1 { write!(f, "\n")?; } } return Ok(()); } } fn iterate(n: usize) -> Vec> { let mut components = Vec::new(); let mut v: Vec = vec![0; n]; loop { let mut sum: usize = 0; for i in &v { sum += *i as usize; } if sum == v.len() { break; } let mut k = 0; for i in 0..v.len() { if v[i] == 1 { v[i] = 0; } else { k = i; break; } } v[k] = 1; components.push(v.clone()); } return components; } impl Graph { fn from_g6(line: &String) -> Graph { let mut chars: Vec = Vec::new(); for character in line.chars() { chars.push((character as i32 - 63) as u8); } // TODO: spec allows multi-byte vector size let size = chars[0] as usize; let bytes = &chars[1..]; let mut matrix: Vec> = vec![vec![0; size]; size]; let mut i = 0; for col in 1..size { for row in 0..col { let bit: i32 = (bytes[i / 6] >> (5 - i % 6) & 1) as i32; matrix[row][col] = bit; matrix[col][row] = bit; i += 1; } } return Graph { size, matrix }; } fn degree(&self, vertex: usize) -> usize { let mut sum: usize = 0; for i in &self.matrix[vertex] { sum += if *i == 0 { 0 } else { 1 } as usize; } return sum; } fn min_degree(&self) -> usize { let mut min = self.size + 1; for i in 0..self.size { let d = self.degree(i); if d < min { min = d; } } return min; } fn get_closure_traced(&self, trace_steps: bool) -> Graph { let mut step = if trace_steps { 2 } else { 1 }; let mut closure = self.clone(); for _ in 0..(closure.size * closure.size) { let mut changed = false; for row in 0..closure.size { for col in 0..closure.size { if row == col || closure.matrix[row][col] != 0 { continue; } let sum = closure.degree(row) + closure.degree(col); if sum >= closure.size { closure.matrix[row][col] = step; if trace_steps { step += 1; } changed = true; } } } if !changed { break; } } return closure; } fn get_hamiltonian_cycle(&self) -> Vec { let closure = self.get_closure_traced(true); let mut cycle = Vec::new(); for i in 0..self.size - 1 { cycle.push(i + 1); } cycle.push(0); loop { let mut start = 0; let mut m = 0; let mut end = start; let mut new_start = start; let mut current = start; loop { let next = cycle[current]; let val = closure.matrix[current][next]; // println!("{current} -> {next} = {val}"); if val > m { m = val; end = current; new_start = next; } current = next; if current == start { break; } } if m == 1 { break; } // println!("New start: {new_start}, end: {end}, m = {m}"); start = new_start; let mut s = start; let mut current = cycle[start]; while current != end { let next = cycle[current]; let u1 = closure.matrix[start][next]; let u2 = closure.matrix[end][current]; if u1 < m && u2 < m { s = current; break; } current = next; } // println!("s = {s}"); let mut new_cycle = Vec::new(); new_cycle.push(start); let mut current = cycle[s]; while current != end { new_cycle.push(current); current = cycle[current]; } new_cycle.push(end); { let mut tmp = Vec::new(); let mut current = cycle[start]; while current != s { tmp.push(current); current = cycle[current]; } tmp.push(s); tmp.reverse(); for i in tmp { new_cycle.push(i); } } for i in 0..self.size - 1 { cycle[new_cycle[i]] = new_cycle[i + 1]; } cycle[new_cycle[self.size - 1]] = new_cycle[0]; } return cycle; } fn cutsets(&self) -> Vec { let mut cs = Vec::new(); for vertices in iterate(self.size) { let mut g = self.clone(); for vertice in 0..g.size { for i in 0..g.size { if vertices[vertice] == 0 { g.matrix[vertice as usize][i as usize] = 0; g.matrix[i as usize][vertice as usize] = 0; } } } let cardinality = vertices.iter().sum::() as usize; cs.push(Cutset { cardinality, vertices: vertices.clone(), graph: g, }); } return cs; } fn max_independent_cutset(&self) -> Cutset { let mut max_cutset = None; for cutset in self.cutsets() { if cutset.graph.is_independent() { match &max_cutset { None => max_cutset = Some(cutset), Some(m_cutset) => { if cutset.cardinality > m_cutset.cardinality { max_cutset = Some(cutset); } } }; } } return max_cutset.unwrap(); } fn dfs(&self, vertex: &usize, visited: &mut Vec) { visited[*vertex] = 1; for i in 0..self.size { if visited[i] == 0 && self.matrix[*vertex][i] != 0 { self.dfs(&i, visited); } } return; } fn count_components(&self) -> usize { let mut visited = vec![0; self.size]; let mut count = 0; while visited.iter().sum::() != visited.len() { let mut next = 0; for i in 0..self.size { if visited[i] == 0 { next = i; break; } } self.dfs(&next, &mut visited); count += 1; } return count; } fn get_closure(&self) -> Graph { self.get_closure_traced(false) } fn is_complete(&self) -> bool { for row in 0..self.size { for col in 0..self.size { if row != col && self.matrix[row][col] == 0 { return false; } } } return true; } fn is_independent(&self) -> bool { for row in 0..self.size { for col in 0..self.size { if row != col && self.matrix[row][col] != 0 { return false; } } } return true; } } fn main() { let stdin = io::stdin(); let mut t = 0; let mut count = 0; for line in stdin.lock().lines() { let line = line.unwrap(); let g = Graph::from_g6(&line); let start = Instant::now(); let closure = g.get_closure(); let is_complete = closure.is_complete(); if is_complete { count += 1; } if is_complete { let components_count = g.count_components(); println!("Components count: {components_count}"); let min_degree = g.min_degree(); println!("Minimal degree: {min_degree}"); println!("Graph: {line}\n{g}"); let cutset = g.max_independent_cutset(); println!("Maximal independent cutset:\n{}", cutset.graph); println!("Included vertices: {:?}", cutset.vertices); println!("Cutset cardinality: {}", cutset.cardinality); let cycle = g.get_hamiltonian_cycle(); print!("Hamiltonian cycle: "); let start = 0; let mut current = start; loop { print!("{}", current + 1); print!(" -> "); current = cycle[current]; if current == start { println!("{}", current + 1); break; } } } let elapsed = start.elapsed(); t += elapsed.as_nanos(); } println!("Count of Hamiltonian graphs: {}", count); println!("Time elapsed: {}s", t as f64 / 1e9); }