题解 | 选药

#include<unordered_map> 
#include<algorithm>
#include<iostream> 
using namespace std;

int main() {
    int n=0; 
    cin>>n; 
    int a[n];
    int f[n];
    int max_b=0; 
    unordered_map<int, int> mp;

    for(int i=0;i<n;i++) 
    {
        int x,y; 
        cin>>x>>y; 
        a[i] = x;
        if(mp.find(x) != mp.end())
         { 
            if(y > mp[x]) mp[x] = y; 
         } 
        else 
        {
            mp[x] = y;
        }
    }
    sort(a, a+n);
    for(int i=0;i<n;i++) {
        int current_b = mp[a[i]];
        if(current_b > max_b) {
            max_b = current_b; // 更新当前最大功效
        }
        f[i] = max_b; 
    }

    int q; 
    cin>>q;
    while(q--) {
        int k; 
        cin>>k;
        if(k < a[0]) {
            cout<<-1<<endl;
            continue;
        }
        int left=0;
        int right=n-1;
        while(left < right)
         {
            int mid=left + (right - left + 1)/2;
            if(a[mid] <= k) left = mid;
            else  right = mid -1;             
        }
        cout<<f[left]<<endl;
    }
    return 0; 
}