1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
#include <bits/stdc++.h>

using namespace std;

#define st first
#define nd second
#define pb push_back
#define rep(i,a,b) for(int i = a; i <= b; i++)
#define irep(i,a,b) for(int i = a; i >= b; i--)
typedef long long ll;
typedef long double ld;
//typedef __int128 int128;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pi; 
typedef pair<double,double> pd;
typedef pair<ll,ll> pl;

const ll max_n = 1007;
ll arr[max_n];

int main(){

    ios::sync_with_stdio(0);
    cin.tie(0);

    ll n,k; cin >> n >> k;
    rep(i,1,n) cin >> arr[i];

    ll ans = 0;
    bool add = 1;
    while(add){
        add = 0;
        rep(i,1,n-1){
            ll diff = abs(arr[i]-arr[i+1]);
            if(diff <= k) continue;
            add = 1;
            ans += diff-k;
            if(arr[i] < arr[i+1])
                arr[i] = arr[i+1]-k;
            else
                arr[i+1] = arr[i]-k;
        }
    }
    
    cout << ans;

    return 0;
}

//g++ -O3 -static -Wall .cpp -std=c++17