[help] Doubt about memory complexity in IOI 2010 Traffic Solution

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Today I wrote a solution for IOI 2010 Traffic

But It exceeds the memory limit.

code

    #include <bits/stdc++.h>
    #include "traffic.h"
    #define pb push_back
     
    using namespace std;
	
    vector<vector<int>> adj(1000000,vector<int>());
 
    map<pair<int,int>,int> m;
 
    int dp(int p,int c,int* P){
        if(m.find((pair<int,int>){p,c})!=m.end())return m[(pair<int,int>){p,c}];
        int ans = P[c];
        for(int v:adj[c]){
            if(v==p)continue;
            ans += dp(c,v,P);
        }
        m.insert({{p,c},ans});
        return ans;
	}
     
    int LocateCentre(int n,int p[],int s[],int d[]){
      for(int i=0;i<n-1;i++){
        adj.at(s[i]).pb(d[i]);
        adj.at(d[i]).pb(s[i]);
      }
      int ans = INT_MAX,index = -1;
      for(int i=0;i<n;i++){
          int local = INT_MIN;
          for(int v:adj[i])local = max(local,dp(i,v,p));
          if(local<ans){
              ans = local;
              index = i;
          }
      }
      return index;
    }

Graph is a tree and has $$$n$$$ $$$(<1e6)$$$ nodes. Therefore i think the total memory will be