蒟蒻求思路改正

#include<bits/stdc++.h>
using namespace std;
int k,n,e,ans;
int main() {
    cin>>k>>e>>n;
    int c[n+1],f[n+1],x[n+1],chengben[n+1];
    for(int i=0;i<e;i++){
        cin>>x[i]>>f[i]>>c[i];
        chengben[i]=(e-x[i])*c[i];
        if(chengben[i-1]>chengben[i]){
            swap(c[i-1],c[i]);
            swap(f[i-1],f[i]);
            swap(c[i-1],c[i]);
        }
    }
    for(int i=0;i<n;i++) {
        if(k<f[i]){
            ans+=k*c[i];
            cout<<ans;
            return 0;
        }else{
            ans+=f[i]*c[i];
            k-=f[i];
        }
    }
    cout<<ans;
    return 0;
}