結果
| 問題 |
No.1323 うしらずSwap
|
| コンテスト | |
| ユーザー |
 沙耶花
|
| 提出日時 | 2020-12-20 00:26:13 |
| 言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
| 結果 |
WA
|
| 実行時間 | - |
| コード長 | 6,993 bytes |
| コンパイル時間 | 2,652 ms |
| コンパイル使用メモリ | 220,476 KB |
| 最終ジャッジ日時 | 2025-01-17 04:01:29 |
|
ジャッジサーバーID （参考情報） |
judge4 / judge1 |
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| ファイルパターン | 結果 |
|---|---|
| sample | AC * 3 |
| other | AC * 37 WA * 22 |
ソースコード
#include <stdio.h>
#include <bits/stdc++.h>
#include <algorithm>
#include <cassert>
#include <limits>
#include <queue>
#include <vector>
namespace atcoder {
template <class Cap, class Cost> struct mcf_graph {
public:
mcf_graph() {}
mcf_graph(int n) : _n(n), g(n) {}
int add_edge(int from, int to, Cap cap, Cost cost) {
assert(0 <= from && from < _n);
assert(0 <= to && to < _n);
int m = int(pos.size());
pos.push_back({from, int(g[from].size())});
g[from].push_back(_edge{to, int(g[to].size()), cap, cost});
g[to].push_back(_edge{from, int(g[from].size()) - 1, 0, -cost});
return m;
}
struct edge {
int from, to;
Cap cap, flow;
Cost cost;
};
edge get_edge(int i) {
int m = int(pos.size());
assert(0 <= i && i < m);
auto _e = g[pos[i].first][pos[i].second];
auto _re = g[_e.to][_e.rev];
return edge{
pos[i].first, _e.to, _e.cap + _re.cap, _re.cap, _e.cost,
};
}
std::vector<edge> edges() {
int m = int(pos.size());
std::vector<edge> result(m);
for (int i = 0; i < m; i++) {
result[i] = get_edge(i);
}
return result;
}
std::pair<Cap, Cost> flow(int s, int t) {
return flow(s, t, std::numeric_limits<Cap>::max());
}
std::pair<Cap, Cost> flow(int s, int t, Cap flow_limit) {
return slope(s, t, flow_limit).back();
}
std::vector<std::pair<Cap, Cost>> slope(int s, int t) {
return slope(s, t, std::numeric_limits<Cap>::max());
}
std::vector<std::pair<Cap, Cost>> slope(int s, int t, Cap flow_limit) {
assert(0 <= s && s < _n);
assert(0 <= t && t < _n);
assert(s != t);
// variants (C = maxcost):
// -(n-1)C <= dual[s] <= dual[i] <= dual[t] = 0
// reduced cost (= e.cost + dual[e.from] - dual[e.to]) >= 0 for all edge
std::vector<Cost> dual(_n, 0), dist(_n);
std::vector<int> pv(_n), pe(_n);
std::vector<bool> vis(_n);
auto dual_ref = [&]() {
std::fill(dist.begin(), dist.end(),
std::numeric_limits<Cost>::max());
std::fill(pv.begin(), pv.end(), -1);
std::fill(pe.begin(), pe.end(), -1);
std::fill(vis.begin(), vis.end(), false);
struct Q {
Cost key;
int to;
bool operator<(Q r) const { return key > r.key; }
};
std::priority_queue<Q> que;
dist[s] = 0;
que.push(Q{0, s});
while (!que.empty()) {
int v = que.top().to;
que.pop();
if (vis[v]) continue;
vis[v] = true;
if (v == t) break;
// dist[v] = shortest(s, v) + dual[s] - dual[v]
// dist[v] >= 0 (all reduced cost are positive)
// dist[v] <= (n-1)C
for (int i = 0; i < int(g[v].size()); i++) {
auto e = g[v][i];
if (vis[e.to] || !e.cap) continue;
// |-dual[e.to] + dual[v]| <= (n-1)C
// cost <= C - -(n-1)C + 0 = nC
Cost cost = e.cost - dual[e.to] + dual[v];
if (dist[e.to] - dist[v] > cost) {
dist[e.to] = dist[v] + cost;
pv[e.to] = v;
pe[e.to] = i;
que.push(Q{dist[e.to], e.to});
}
}
}
if (!vis[t]) {
return false;
}
for (int v = 0; v < _n; v++) {
if (!vis[v]) continue;
// dual[v] = dual[v] - dist[t] + dist[v]
// = dual[v] - (shortest(s, t) + dual[s] - dual[t]) + (shortest(s, v) + dual[s] - dual[v])
// = - shortest(s, t) + dual[t] + shortest(s, v)
// = shortest(s, v) - shortest(s, t) >= 0 - (n-1)C
dual[v] -= dist[t] - dist[v];
}
return true;
};
Cap flow = 0;
Cost cost = 0, prev_cost = -1;
std::vector<std::pair<Cap, Cost>> result;
result.push_back({flow, cost});
while (flow < flow_limit) {
if (!dual_ref()) break;
Cap c = flow_limit - flow;
for (int v = t; v != s; v = pv[v]) {
c = std::min(c, g[pv[v]][pe[v]].cap);
}
for (int v = t; v != s; v = pv[v]) {
auto& e = g[pv[v]][pe[v]];
e.cap -= c;
g[v][e.rev].cap += c;
}
Cost d = -dual[s];
flow += c;
cost += c * d;
if (prev_cost == d) {
result.pop_back();
}
result.push_back({flow, cost});
prev_cost = cost;
}
return result;
}
private:
int _n;
struct _edge {
int to, rev;
Cap cap;
Cost cost;
};
std::vector<std::pair<int, int>> pos;
std::vector<std::vector<_edge>> g;
};
} // namespace atcoder
using namespace atcoder;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000
int H,W;
vector<string> S;
vector<int> dy = {0,0,1,-1},dx = {1,-1,0,0};
vector<vector<int>> get(int r,int c){
queue<pair<int,int>> Q;
vector<vector<int>> dis(H,vector<int>(W,Inf));
dis[r][c] = 0;
Q.emplace(r,c);
while(Q.size()>0){
int y = Q.front().first,x = Q.front().second;
Q.pop();
rep(i,4){
int yy = y+dy[i],xx = x+dx[i];
if(yy<0||yy>=H||xx<0||xx>=W)continue;
if(S[yy][xx]=='#')continue;
if(dis[yy][xx]!=Inf)continue;
dis[yy][xx] = dis[y][x]+1;
Q.emplace(yy,xx);
}
}
return dis;
}
int main(){
cin>>H>>W;
S.resize(H);
int r0,c0,r1,c1;
cin>>r0>>c0>>r1>>c1;
r0--,c0--,r1--,c1--;
rep(i,H){
cin>>S[i];
}
auto d0 = get(r0,c0),d1 = get(r1,c1);
if(d0[r1][c1]==Inf)cout<<-1<<endl;
else{
int D = d0[r1][c1];
int cnt = 0;
rep(i,H){
rep(j,W){
if(d0[i][j] + d1[i][j]==D)cnt++;
}
}
if(cnt>D+1){
cout<<2*D<<endl;
return 0;
}
else{
rep(i,H){
rep(j,W){
if(d0[i][j]==Inf)continue;
if(d0[i][j]+d1[i][j]==D)continue;
rep(k,4){
int ii = i+dy[k],jj = j+dx[k];
if(d0[ii][jj]+d1[ii][jj]==D && d0[ii][jj]!=0 && d1[ii][jj]!=0){
cout<<2*D+2<<endl;
return 0;
}
}
}
}
}
mcf_graph<int,int> G(2*H*W);
rep(i,H){
rep(j,W){
if(S[i][j]=='#')continue;
G.add_edge(2*(i*W+j),2*(i*W+j)+1,1,0);
rep(k,4){
int ii = i,jj = j;
ii += dy[k],jj += dx[k];
if(S[ii][jj]=='#')continue;
G.add_edge(2*(i*W+j)+1,2*(ii*W+jj),1,1);
}
}
}
auto ans = G.flow(2*(r0*W+c0)+1,2*(r1*W+c1),2);
if(ans.first<2)cout<<-1<<endl;
else cout<<ans.second<<endl;
}
return 0;
}