P1314 [NOIP 2011 提高组] 聪明的质监员

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#include<bits/stdc++.h>
using namespace std;

typedef long long LL;
const int N=2e5+10;
int n,m;
LL s;
int w[N],v[N];
int l[N],r[N];
LL s1[N],s2[N];

LL check(int x)
{
    for(int i=1;i<=n;i++){
        if(w[i]>=x){
            s1[i]=s1[i-1]+1;
            s2[i]=s2[i-1]+v[i];
        }else{
            s1[i]=s1[i-1];
            s2[i]=s2[i-1];
        }
    }
    LL Y=0;
    for(int i=1;i<=m;i++){
        LL cnt=s1[r[i]]-s1[l[i]-1];
        LL sum=s2[r[i]]-s2[l[i]-1];
        Y+=cnt*sum;
    }

    return Y;
}

int main()
{
    ios::sync_with_stdio(0),cin.tie(0);

    cin>>n>>m>>s;

	int max_w=0;
    for(int i=1;i<=n;i++){
        cin>>w[i]>>v[i];
        max_w=max(w[i],max_w);
    }

    for(int i=1;i<=m;i++){
        cin>>l[i]>>r[i];
    }

    int L=0,R=max_w+2;
    LL ans=1e18;
    
    while(L<=R){
        int mid=L+(R-L)/2;
        LL Y=check(mid);
        if(ans>abs(Y-s)){
            ans=abs(Y-s);
        }
        if(Y-s>0){
            L=mid+1;
        }else{
            R=mid-1;
        }
    }

    cout<<ans<<endl;

    return 0;
}