2018普及组-T3 摆渡车

题目描述
https://www.luogu.org/problemnew/show/P5017

AC代码，抄的，原地址为：
https://www.cnblogs.com/yzhang-rp-inf/p/9769530.html

#include<iostream>
#include<algorithm>
using namespace std;
int main(){
    int n,m;
    cin>>n>>m;
    int a[10000]={0};
    for (int i=0;i<n;i++){
        cin>>a[i];
    }
    
    sort(a,a+n);
    
    int i=0;
    int ans=0,d=a[0];
    while (i<n){
        int j=1;
        while (a[i]==a[i+1]&&i<n){
            j++;
            i++;
        }
        ans+=(d-a[i])*j;
        d+=m;
        i++;
    }
    cout<<ans;
    return 0;
}