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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#50181 | #4809. Maximum Range | sealnot123# | RE | 3ms | 5840kb | C++ | 6.2kb | 2022-09-25 05:17:23 | 2022-09-25 05:17:24 |
Judging History
answer
#include<bits/stdc++.h>
#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define rep(i,a,b) for(int i=a; i<(b); ++i)
#define FOR(i,a,b) for(int i=a; i<(b); ++i)
#define all(x) begin(x),end(x)
#define sz(x) (int)(x).size()
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
const int N = 100005;
int n, m;
vector<vector<pii>> edge;
int cnt = 0;
int comp[N];
vvi node_in_comp;
vector<vector<pii>> edge_in_comp;
int t = 0;
int idx[N], lowlink[N];
stack<int> stk;
void dfs(int u, int p) {
idx[u] = lowlink[u] = ++t;
stk.push(u);
for(pii e: edge[u]) {
int v = e.x;
if(v == p) continue;
if(idx[v]) lowlink[u] = min(lowlink[u], idx[v]);
else {
dfs(v, u);
lowlink[u] = min(lowlink[u], lowlink[v]);
}
}
if(idx[u] == lowlink[u]) {
node_in_comp.eb();
while(1) {
int x = stk.top();
stk.pop();
comp[x] = cnt;
node_in_comp[cnt].eb(x);
if(x == u) break;
}
++cnt;
}
}
// =======================================================
ll max_range = -1e18;
vector<int> ans;
struct edge_ {
int v, cap, pos, num;
edge_(int _v, int _cap, int _pos, int _num) {
v = _v;
cap = _cap;
pos = _pos;
num = _num;
}
};
vector<vector<edge_>> g;
queue<int> bfs;
int dp[N], from[N];
int used[N];
int edge_count;
void add_edge(int a, int b, int c, bool oneway = false) {
int posa = sz(g[a]);
int posb = sz(g[b]);
g[a].eb(b, 1, posb, edge_count);
if(!oneway) g[b].eb(a, 1, posa, edge_count);
else g[b].eb(a, 0, posa, edge_count);
++edge_count;
}
void st(int source, int sink, int c) {
for(int e : node_in_comp[c]) {
dp[e] = -1;
from[e] = -1;
}
dp[sink] = from[sink] = -1;
dp[source] = 0;
from[source] = -1;
bfs.push(source);
while(!bfs.empty()) {
int u = bfs.front();
bfs.pop();
for(edge_ &e : g[u]) {
if(e.cap == 0) continue;
if(dp[e.v] != -1) continue;
dp[e.v] = dp[u]+1;
from[e.v] = u;
bfs.push(e.v);
}
}
}
void augment(int source, int sink) {
int now = sink;
assert(from[sink] != -1);
while(now != source) {
int next = from[now];
for(edge_ &e: g[next]) {
if(e.v == now) {
assert(e.cap > 0);
e.cap--;
g[now][e.pos].cap++;
used[e.num] ^= 1;
break;
}
}
now = next;
}
}
vi temp_path;
void dfs_path(int now) {
if(now < n) {
temp_path.pb(now);
}
for(edge_ &e: g[now]) {
if(used[e.num]) {
used[e.num] ^= 1;
dfs_path(e.v);
}
}
}
vi find_path(pair<pii,int> Max, pair<pii,int> Min) {
if(Max.x.x > Max.x.y) swap(Max.x.x, Max.x.y);
if(Min.x.x > Min.x.y) swap(Min.x.x, Min.x.y);
int cur = comp[Max.x.x];
int comp_sz = sz(node_in_comp[cur]);
int source = n;
int sink = n+1;
// add edge
for(int u : node_in_comp[cur]) {
for(auto e : edge_in_comp[u]) {
int v = e.x;
if(u > v) continue;
if(pii(u,v) == Max.x || pii(u,v) == Min.x) {
continue;
}
add_edge(u, v, 1);
}
}
add_edge(source, Max.x.x, 1, true);
add_edge(source, Max.x.y, 1, true);
add_edge(Min.x.x, sink, 1, true);
add_edge(Min.x.y, sink, 1, true);
// bfs twice
rep(i,0,2){
st(source, sink, cur);
augment(source, sink);
}
// find path
temp_path.clear();
dfs_path(source);
// TODO: clean up
rep(i, 0, edge_count) {
used[i] = 0;
}
edge_count = 0;
g[source].clear();
g[sink].clear();
for(int u : node_in_comp[cur]) {
g[u].clear();
}
// debug
/*
printf("Comp: ");
for(int u: node_in_comp[cur]) printf("%d ",u);
puts("");
printf("Max: (%d,%d),%d\n",Max.x.x,Max.x.y,Max.y);
printf("Min: (%d,%d),%d\n",Min.x.x,Min.x.y,Min.y);
printf("Path: ");
for(int u: temp_path) {
printf("%d ",u);
}
puts("");
*/
return temp_path;
}
void solve() {
scanf("%d %d",&n,&m);
edge.resize(n);
edge_in_comp.resize(n);
g.resize(n+2);
rep(i, 0, m) {
int a, b, c;
scanf("%d %d %d",&a,&b,&c);
--a;
--b;
edge[a].eb(b,c);
edge[b].eb(a,c);
}
dfs(0, -1);
rep(i, 0, cnt) {
// find max edge, min edge
pair<pii,int> Max(pii(0,0),-(1<<30)), Min(pii(0,0),(1<<30));
for(int u : node_in_comp[i]) {
for(pii e : edge[u]) {
if(comp[e.x] == comp[u]) {
edge_in_comp[u].pb(e);
if(e.y > Max.y) Max = {pii(u,e.x),e.y};
if(e.y < Min.y) Min = {pii(u,e.x),e.y};
}
}
}
if(max_range < Max.y-Min.y) {
// Find path
if(Max.x == Min.x) {
bool found= false;
if(Max.x.x > Max.x.y) swap(Max.x.x,Max.x.y);
for(int u : node_in_comp[i]) {
for(pii e : edge[u]) {
if(comp[e.x] == comp[u]) {
int a = u;
int b = e.x;
if(a > b) swap(a,b);
if(pii(a,b) != Max.x){
Min.x = pii(a,b);
found = true;
break;
}
}
}
if(found) break;
}
}
ans = find_path(Max, Min);
max_range = Max.y-Min.y;
}
}
printf("%lld\n",max_range);
printf("%d\n",sz(ans));
for(int e : ans) printf("%d ",e+1);
}
int main() {
solve();
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 3ms
memory: 5840kb
input:
5 7 1 2 1 1 3 -2 2 3 1 3 4 3 4 5 1 1 5 -1 2 5 2
output:
5 4 3 1 5 4
result:
ok ok
Test #2:
score: -100
Dangerous Syscalls
input:
99997 100000 12238 99016 352755196 99016 25485 -412473602 25485 2440 991507552 2440 31171 -181894654 36970 2440 -800167579 2440 41865 -148191946 96629 31171 847888506 36970 95740 395546542 27992 2440 647886610 99016 29557 369124914 80795 27992 -673871966 36970 3509 573208857 57672 29557 874406776 41...