Educational Codeforces Round 55 (Rated for Div. 2) C. Multi-Subject Competition(思维)

#include <bits/stdc++.h>
#define ll long long
#define maxn 200005
using namespace std;
vector<ll> v[maxn],ans[maxn];
ll n,m;

bool cmp(ll a,ll b){
	return a > b;
}

int main()
{
	ll xx = 0;
	scanf("%lld%lld",&n,&m);
	for(int i=1;i<=n;i++){
		ll x,y;
		scanf("%lld%lld",&x, &y);
		v[x].push_back(y);
	}
	for(int i=1;i<=m;i++){
		sort(v[i].begin(), v[i].end(), cmp);
	}
	for(int i=1;i<=m;i++){
		ll sum = 0;
		for(int j=0;j<v[i].size();j++){
			sum += v[i][j];
			ans[j].push_back(sum);
		}
	}
	for(int i=0;i<n;i++){
		ll sum = 0;
		for(int j=0;j<ans[i].size();j++){
			if(ans[i][j] > 0){
				sum += ans[i][j];
			}
			xx = max(xx, sum);
		}
	}
	cout<<xx<<endl;
	return 0;
}