結果
| 問題 |
No.3024 全単射的
|
| ユーザー |
 atcoder8
|
| 提出日時 | 2025-02-15 13:22:35 |
| 言語 | Rust (1.83.0 + proconio) |
| 結果 |
RE
|
| 実行時間 | - |
| コード長 | 14,935 bytes |
| コンパイル時間 | 14,978 ms |
| コンパイル使用メモリ | 386,788 KB |
| 実行使用メモリ | 54,644 KB |
| 最終ジャッジ日時 | 2025-02-15 13:22:54 |
| 合計ジャッジ時間 | 17,938 ms |
|
ジャッジサーバーID （参考情報） |
judge5 / judge1 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 18 RE * 4 |
ソースコード
use maxflow::MfGraph;
use proconio::{input, marker::Usize1};
fn main() {
input! {
(n, m): (usize, usize),
xy: [(Usize1, Usize1); n],
}
let source = n + m;
let sink = n + m + 1;
let mut mf_graph = MfGraph::<usize>::new(n + m + 2);
for bot_idx in 0..n {
mf_graph.add_edge(source, bot_idx, 1);
}
for (bot_idx, &(x, y)) in xy.iter().enumerate() {
mf_graph.add_edge(bot_idx, n + x, 1);
mf_graph.add_edge(bot_idx, n + y, 1);
}
for prize_idx in 0..m {
mf_graph.add_edge(n + prize_idx, sink, 1);
}
println!("{}", mf_graph.flow(source, sink));
}
pub mod maxflow {
use std::{
collections::VecDeque,
ops::{Add, Sub},
};
pub trait Zero {
fn zero() -> Self;
fn is_zero(&self) -> bool;
}
pub trait MaxValue {
fn max_value() -> Self;
}
pub trait Capacity:
std::fmt::Debug
+ Clone
+ Copy
+ Ord
+ Add<Self, Output = Self>
+ Sub<Self, Output = Self>
+ Zero
+ MaxValue
{
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct FlowEdge<Cap> {
/// Node that is the source of the flow.
pub from: usize,
/// Node that is the destination of the flow.
pub to: usize,
/// Upper limit of flow through this edge.
pub capacity: Cap,
/// Current flow for this edge.
pub flow: Cap,
}
impl<Cap> FlowEdge<Cap>
where
Cap: Capacity,
{
/// Create an edge by specifying endpoints and flow limit.
/// Initial flow amount is zero.
pub fn new(from: usize, to: usize, capacity: Cap) -> Self {
Self {
from,
to,
capacity,
flow: Cap::zero(),
}
}
/// Returns the difference between the upper flow limit and the current flow amount.
pub fn rem_capacity(&self) -> Cap {
self.capacity - self.flow
}
}
#[derive(Debug, Clone)]
pub struct MfGraph<Cap> {
/// Number of graph edges.
node_num: usize,
/// List of edges of this graph.
edges: Vec<FlowEdge<Cap>>,
/// For each node, a list containing a list of indices of edges with that node as head.
graph: Vec<Vec<usize>>,
/// For each node, a list containing a list of indices of edges with that node as tail.
inv_graph: Vec<Vec<usize>>,
}
impl<Cap> MfGraph<Cap>
where
Cap: Capacity,
{
/// Creates an empty directed graph with `node_num` nodes.
pub fn new(node_num: usize) -> Self {
Self {
node_num,
graph: vec![vec![]; node_num],
inv_graph: vec![vec![]; node_num],
edges: vec![],
}
}
/// Add an edge from the node `from` to the node `to` with flow limit `capacity`.
pub fn add_edge(&mut self, from: usize, to: usize, capacity: Cap) {
assert!(
from < self.node_num && to < self.node_num,
"`from` and `to` must be smaller than number of nodes."
);
assert!(capacity >= Cap::zero(), "`capacity` must be non-negative.");
let edge_idx = self.edges.len();
self.edges.push(FlowEdge::new(from, to, capacity));
self.graph[from].push(edge_idx);
self.inv_graph[to].push(edge_idx);
}
/// Returns the state of the `edge_idx` th (0-based) edge.
pub fn get_edge(&self, edge_idx: usize) -> FlowEdge<Cap> {
assert!(
edge_idx < self.edges.len(),
"The number of edges is {}, but {} was specified.",
self.edges.len(),
edge_idx
);
self.edges[edge_idx]
}
/// Returns a list of edge states added to the graph.
pub fn get_edges(&self) -> &Vec<FlowEdge<Cap>> {
&self.edges
}
/// Creates a list of `level` for each node,
/// where `level` is the distance from `source` using edges or inverses
/// where the current flow amount is less than the upper limit.
fn find_levels(&self, source: usize, sink: usize) -> Vec<Option<usize>> {
let mut levels: Vec<Option<usize>> = vec![None; self.node_num];
let mut queue = VecDeque::from([(source, 0)]);
while let Some((cur_node, cand_level)) = queue.pop_front() {
if levels[cur_node].is_some() {
continue;
}
levels[cur_node] = Some(cand_level);
if cur_node == sink {
continue;
}
let next_bfs_nodes = self.graph[cur_node]
.iter()
.filter(|&&edge_idx| !self.edges[edge_idx].rem_capacity().is_zero())
.map(|&edge_idx| self.edges[edge_idx].to)
.chain(
self.inv_graph[cur_node]
.iter()
.filter(|&&edge_idx| !self.edges[edge_idx].flow.is_zero())
.map(|&edge_idx| self.edges[edge_idx].from),
)
.map(|next_node| (next_node, cand_level + 1));
queue.extend(next_bfs_nodes);
}
levels
}
/// Increases the flow from `source` to `sink` by the maximum flow `flow_limit` and returns the increased flow amount.
fn increase_flow(&mut self, source: usize, sink: usize, flow_limit: Cap) -> Cap {
let levels = self.find_levels(source, sink);
let Some(sink_level) = levels[sink] else {
return Cap::zero();
};
let select_edge = |cur_node: usize,
edge_progresses: &mut [usize],
inv_edge_progresses: &mut [usize],
edges: &[FlowEdge<Cap>]| {
let cur_level = levels[cur_node].unwrap();
let edge_progress = &mut edge_progresses[cur_node];
while *edge_progress < self.graph[cur_node].len() {
let edge_idx = self.graph[cur_node][*edge_progress];
let edge = edges[edge_idx];
if levels[edge.to] == Some(cur_level + 1) && !edge.rem_capacity().is_zero() {
return Some((edge_idx, false));
}
*edge_progress += 1;
}
let inv_edge_progress = &mut inv_edge_progresses[cur_node];
while *inv_edge_progress < self.inv_graph[cur_node].len() {
let edge_idx = self.inv_graph[cur_node][*inv_edge_progress];
let edge = edges[edge_idx];
if levels[edge.from] == Some(cur_level + 1) && !edge.flow.is_zero() {
return Some((edge_idx, true));
}
*inv_edge_progress += 1;
}
None
};
let push_dfs_node = |cur_node: usize,
edge_progresses: &mut [usize],
inv_edge_progresses: &mut [usize],
edges: &[FlowEdge<Cap>],
stack: &mut Vec<DFSNode<Cap>>| {
let Some((edge_idx, inverse)) =
select_edge(cur_node, edge_progresses, inv_edge_progresses, edges)
else {
return;
};
let edge = edges[edge_idx];
let (next_node, next_rem_capacity) = if inverse {
(edge.from, edge.flow)
} else {
(edge.to, edge.rem_capacity())
};
stack.push(DFSNode::Backward {
cur_node,
edge_idx,
inverse,
});
stack.push(DFSNode::Forward {
cur_node: next_node,
rem_capacity: next_rem_capacity,
});
};
enum DFSNode<Cap> {
Forward {
cur_node: usize,
rem_capacity: Cap,
},
Backward {
cur_node: usize,
edge_idx: usize,
inverse: bool,
},
}
struct FlowState<Cap> {
flow_limit: Cap,
flow: Cap,
}
let mut edge_progresses = vec![0; self.node_num];
let mut inv_edge_progresses = vec![0; self.node_num];
let mut stack = vec![DFSNode::Forward {
cur_node: source,
rem_capacity: flow_limit,
}];
stack.reserve(2 * sink_level);
let mut flow_state_stack: Vec<FlowState<Cap>> = vec![];
flow_state_stack.reserve(sink_level);
while let Some(dfs_node) = stack.pop() {
match dfs_node {
DFSNode::Forward {
cur_node,
rem_capacity,
} => {
let cur_flow_limit = match flow_state_stack.last() {
Some(prev_flow_state) => {
prev_flow_state.flow_limit - prev_flow_state.flow
}
None => flow_limit,
}
.min(rem_capacity);
if cur_node == sink {
flow_state_stack.push(FlowState {
flow_limit: cur_flow_limit,
flow: cur_flow_limit,
});
continue;
}
flow_state_stack.push(FlowState {
flow_limit: cur_flow_limit,
flow: Cap::zero(),
});
push_dfs_node(
cur_node,
&mut edge_progresses,
&mut inv_edge_progresses,
&self.edges,
&mut stack,
);
}
DFSNode::Backward {
cur_node,
edge_idx,
inverse,
} => {
let next_flow_state = flow_state_stack.pop().unwrap();
let edge = &mut self.edges[edge_idx];
if inverse {
edge.flow = edge.flow - next_flow_state.flow;
} else {
edge.flow = edge.flow + next_flow_state.flow;
}
let cur_flow_state = flow_state_stack.last_mut().unwrap();
cur_flow_state.flow = cur_flow_state.flow + next_flow_state.flow;
if cur_flow_state.flow_limit == cur_flow_state.flow {
continue;
}
if inverse {
inv_edge_progresses[cur_node] += 1;
} else {
edge_progresses[cur_node] += 1;
}
push_dfs_node(
cur_node,
&mut edge_progresses,
&mut inv_edge_progresses,
&self.edges,
&mut stack,
);
}
}
}
flow_state_stack[0].flow
}
/// Flows from `source` to `sink` as much as possible, and returns the flowed amount.
/// The flow limit is set to the maximum of the values represented by the capacity type.
pub fn flow(&mut self, source: usize, sink: usize) -> Cap {
self.flow_with_capacity(source, sink, Cap::max_value())
}
/// Flows from `source` to `sink` as much as possible, with the maximum flow as `flow_limit`, and returns the flowed amount.
pub fn flow_with_capacity(&mut self, source: usize, sink: usize, flow_limit: Cap) -> Cap {
assert!(
source < self.node_num && sink < self.node_num,
"`source` and `sink` must be smaller than number of nodes."
);
let mut max_flow = Cap::zero();
while max_flow < flow_limit {
let flow = self.increase_flow(source, sink, flow_limit - max_flow);
if flow.is_zero() {
break;
}
max_flow = max_flow + flow;
}
max_flow
}
/// Finds for each node if it is reachable from `source` using the edge or the inverse edge,
/// where the current flow is less than the upper limit.
pub fn min_cut(&self, source: usize) -> Vec<bool> {
let mut visited = vec![false; self.node_num];
let mut queue = VecDeque::from([source]);
while let Some(cur_node) = queue.pop_front() {
if visited[cur_node] {
continue;
}
visited[cur_node] = true;
for &edge_idx in &self.graph[cur_node] {
let edge = self.edges[edge_idx];
if !edge.rem_capacity().is_zero() {
queue.push_back(edge.to);
}
}
for &edge_idx in &self.inv_graph[cur_node] {
let edge = self.edges[edge_idx];
if !edge.flow.is_zero() {
queue.push_back(edge.from);
}
}
}
visited
}
}
macro_rules! impl_capacity_for_unsigned_integer {
( $( $uint: ty ), * ) => {
$(
impl Zero for $uint {
fn zero() -> Self {
0
}
fn is_zero(&self) -> bool {
self == &0
}
}
impl MaxValue for $uint {
fn max_value() -> Self {
<$uint>::MAX
}
}
impl Capacity for $uint {}
)*
};
}
impl_capacity_for_unsigned_integer!(u8, u16, u32, u64, u128, usize);
}