Submission #1269975

#	Time	Username	Problem	Language	Result	Execution time	Memory
1269975		herominhsteve	Rigged Roads (NOI19_riggedroads)	C++20	100 / 100	422 ms	59028 KiB

riggedroads

#include <bits/stdc++.h>
#define el '\n'
#define FNAME "NOI19_riggedroads"
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,n) memset(x,(n),sizeof(x))
using namespace std;
const long long MOD = (long long) 1e9+7;
template<class X,class Y> bool minimize(X &a,Y b){ if (a>b) {a=b; return true;} return false;}
template<class X,class Y> bool maximize(X &a,Y b){ if (a<b) {a=b; return true;} return false;}

void setup(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
	if (fopen(FNAME".inp","r")){
		freopen(FNAME".inp","r",stdin);
		freopen(FNAME".out","w",stdout);
	}
}

const int MAXN = 3e5 + 5;

int n,m;
vector<int> graph[MAXN];
bool inMST[MAXN];

inline pair<int,int> uv(int u,int v){
    return make_pair(min(u,v),max(u,v));
}
map<pair<int,int>,int> eID;

vector<pair<int,int>> edges;

void init(){
	cin>>n>>m;
    for (int i=0;i<m;i++){
        int u,v;
        cin>>u>>v;
        edges.emplace_back(u,v);
        eID[uv(u,v)] = i;
    }
    for (int i=1;i<n;i++){
        int e; cin>>e; e--;
        inMST[e]=1;
        int u,v; tie(u,v) = edges[e];
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
}

int depth[MAXN],parent[MAXN];
bool visited[MAXN];

void dfs(int u,int pre){
    visited[u] = 1;
    parent[u] = pre;
    for (int v : graph[u]){
        if (!visited[v]){
            depth[v] = depth[u] + 1;
            dfs(v,u);
        }
    }
}

namespace DSU{
    vector<int> parent,power,rep;
    void make_set(){
        parent.resize(n+1,0);
        power.resize(n+1,1);
        rep.assign(n+1,0);
        for (int i=1;i<=n;i++){
            parent[i]=i;
            power[i]=1;
            rep[i] = i;
        }
    }
    int find(int u){
        if (u==parent[u]) return u;
        return parent[u]=find(parent[u]);
    }
    bool Union(int u,int v){
        u=find(u);
        v=find(v);
        if (u==v) return false;
        if (power[u]<power[v]) swap(u,v);
        parent[v]=u;
        power[u]+=power[v];
        if (depth[rep[u]] > depth[rep[v]]) 
            rep[u] = rep[v];
        return true;
    }
    int getRep(int u){
        return rep[find(u)];
    }
};

void sol(){
	dfs(1,1);
    DSU::make_set();
    
    int cur=0;

    vector<int> res(m,0);
    for (int i=0;i<m;i++){
        int u,v; tie(u,v) = edges[i];
        if (inMST[i]){
            if (!res[i]){
                res[i] = ++cur;
                DSU::Union(u,v);
            }
        } else{
            u = DSU::getRep(u);
            v = DSU::getRep(v);
            vector<int> indices;

            while (u ^ v){
                if (depth[u] < depth[v]) swap(u,v);
                indices.push_back(eID[uv(u,parent[u])]);
                DSU::Union(u,parent[u]);
                u = DSU::getRep(u);
            }

            sort(allof(indices));
            for (int x : indices) res[x]=++cur;
            res[i] = ++cur;
        }
    }
    for (int x : res) cout<<x<<" ";
}

int main(){
    setup();
    init();
    sol();
}

Compilation message (stderr)

riggedroads.cpp: In function 'void setup()':
riggedroads.cpp:16:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |                 freopen(FNAME".inp","r",stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
riggedroads.cpp:17:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |                 freopen(FNAME".out","w",stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 19 / 19
• Subtask 3: 9 / 9
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 12 / 12
• Subtask 7: 32 / 32