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
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
#include <iostream>
#include <vector>

using namespace std;

bool decide(int a, int b){
    return a > b;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n,k,result = 0, temp;
    cin >> n >> k;
    vector<int> v(n);
    for(int i=0; i < n; ++i){
        cin >> v[i];
    }

    int max = 0;
    int index = 0;
    for(int i = 0; i < n; ++i){
        if(v[i] > max){
            max = v[i];
            index = i;
        }
    }
    int i = index;
    int direction = index == n-1 ? -1 : 1;
    int j = i + direction;
    bool changed = false;
    int strike = 0;
    while((i < n) && (i >= 0)){
        if(decide(v[i], v[j])){
            int temp = (v[i] - v[j]);
            if(temp > k){
                changed = true;
                result += temp - k;
                v[j] += temp - k;
            }
        } else {
            int temp = (v[j] - v[i]);
            if(temp > k){
                changed = true;
                result += temp - k;
                v[i] += temp - k;
            }
        }
        i += direction;
        j = i + direction;
        if(i >= n || i < 0 || j >= n || j < 0){
            if(changed){
                strike = 0;
                changed = false;
            } else {
                strike++;
            }
            if(strike == 2){
                break;
            }
            direction *= -1;
            i += direction;
            j = i + direction;
        }
    }

    cout << result << "\n";
    return 0;
}