Language: C++

#include <iostream>
#include <map>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
const int MAXN = 1e5+5;
map<int,pair<int,int>> curColours;
vector<map<int,pair<int,int>>> colourData;

vector<pair<int,int>> v1[MAXN];
int level[MAXN];
int parent[MAXN];
int parentedge[MAXN];
int dist[MAXN];
vector<pair<int,int>> edgedata;
int dp[MAXN][24];
bool special[MAXN];
bool checkedi[MAXN];
void dfs1(int curr,int par){
    for(auto z:v1[curr]){
        int x = z.first;
        if(x == par){
            continue;
        }
        level[x] = level[curr] + 1;
        parent[x] = curr;
        parentedge[x] = z.second;
        dist[x] = dist[curr]+edgedata[parentedge[x]].second;
        dfs1(x,curr);
    }
}
void dfs2(int curr,int par){
   
    if(special[curr]){
        
        colourData[curr] = curColours;
    }
    for(auto x:v1[curr]){
        
        if(x.first == par){
            continue;
        }
        int ind = x.second;
        //cout<<curr<<" "<<x.first<<" "<<ind<<endl;
        int col = edgedata[ind].first;
        int dist = edgedata[ind].second;
        if(!curColours.count(col)){
            curColours.insert(make_pair(col,make_pair(0,0)));
        }
        curColours[col].first++;
        curColours[col].second+=dist;
        dfs2(x.first,curr);
        
        curColours[col].first--;
        curColours[col].second-=dist;
        
        if(curColours[col].first == 0){
            curColours.erase(col);
        }
    }
    
}
int lca(int u,int v){
    if(level[u]<level[v]){
        swap(u,v);
    }
    for(int i=20;i>=0;i--){
        if(level[u]-(1<<i)>=level[v]){
            u = dp[u][i];
        }
    }
    if(u==v){
        return u;
    }
    for(int i=20;i>=0;i--){
        if(dp[u][i]!=dp[v][i] && dp[u][i]!=-1 && dp[v][i]!=-1){
            u = dp[u][i];
            v=dp[v][i];
        }
    }
    return parent[u];
}
pair<int,int> getdata(int v,int colour){
    if(v == -1){
        cout<<1234567<<endl;
        return 0;
    }
 //   cout<<v<<" "<<parent[v]<<" "<<special[v]<<endl;
    if(special[v]){
        if(!colourData[v].count(colour)){
            return make_pair(0,0);
        }else{
            return colourData[v][colour];
        }
    }
    
    pair<int,int> prev = getdata(parent[v],colour);
    int ind = parentedge[v];
    if(edgedata[ind].first == colour){
        prev.first++;
        prev.second+=edgedata[ind].second;
    }
    return prev;
}
int rootdist(int curr,pair<int,int> data,int newLen){
    return dist[curr]-data.second+(data.first*newLen);
}
int main(){
    int n;
    cin>>n;
    int q;
    cin>>q;
    for(int i=0;i<n-1;i++){
        int a,b,c,d;
        cin>>a>>b>>c>>d;
        edgedata.push_back(make_pair(c,d));
        v1[a].push_back(make_pair(b,i));
        v1[b].push_back(make_pair(a,i));
    }
    parent[1] = -1;
    level[1] = 0;
    dist[1] = 0;
    dfs1(1,-1);
    priority_queue<pair<int,int>> pq;
    for(int i=1;i<=n;i++){
        pq.push(make_pair(level[i],i));
    }
    for(int i=0;i<=n;i++){
        special[i] = false;
        checkedi[i] = false;
    }
    
    int cnt = 1;
    special[1] = true;
    checkedi[1] = true;
    while(!pq.empty()){
        int curr= pq.top().second;
        pq.pop();
       
        if(checkedi[curr]){
            continue;
        }
        for(int i=0;i<350;i++){
            curr = parent[curr];
            if(special[curr]){
                break;
            }
            checkedi[curr] = true;
        }
        special[curr]= true;
        
    }
    
    for(int i=0;i<=n;i++){
        map<int,pair<int,int>> blank;
        colourData.push_back(blank);
    }
    dfs2(1,-1);
    for(int i=1;i<=n;i++){
        for(int j=0;j<=20;j++){
            dp[i][j] = -1;
        }
    }
    for(int i=1;i<=n;i++){
        dp[i][0] = parent[i];
    }
    for(int j=1;j<=n;j++){
        for(int i=1;i<=n;i++){
            if(dp[i][j-1] == -1){
                dp[i][j] = -1;
            }else{
                dp[i][j] = max(dp[i][j],dp[dp[i][j-1]][j-1]);
            }
        }
    }
    while(q--){
        int a,b,c,d;
        cin>>a>>b>>c>>d;
        int e = lca(c,d);
        //cout<<e<<endl;
        cout<<rootdist(c,getdata(c,a),b)+rootdist(d,getdata(d,a),b)-2*rootdist(e,getdata(e,a),b)<<"\n";
  }
}


Compiler output:
a.cc: In function 'std::pair<int, int> getdata(int, int)':
a.cc:87:16: error: could not convert '0' from 'int' to 'std::pair<int, int>'
   87 |         return 0;
      |                ^
      |                |
      |                int