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| #include <cstdio>
#include <queue>
using namespace std;
template <class Type>
void read(Type &x)
{
char c;
bool flag = false;
while ((c = getchar()) < '0' || c > '9')
c == '-' && (flag = true);
x = c - '0';
while ((c = getchar()) >= '0' && c <= '9')
x = (x << 3) + (x << 1) + c - '0';
if (flag) x = ~x + 1;
}
template <class Type, class ...rest>
void read(Type &x, rest &...y) { read(x), read(y...); }
template <class Type>
void write(Type x)
{
if (x < 0) putchar('-'), x = ~x + 1;
if (x > 9) write(x / 10);
putchar(x % 10 + '0');
}
typedef long long LL;
const int N = 5e5 + 10, M = 20;
int n, m, L, R, s[N];
int lg[N], st[N][M];
int smin (int a, int b)
{
return s[a] > s[b] ? a : b;
}
void init()
{
for (int i = 2; i <= n; ++i) lg[i] = lg[i >> 1] + 1;
for (int i = 1; i <= n; ++i) st[i][0] = i;
for (int k = 1; 1 << k <= n; ++k)
for (int i = 1; i + (1 << k) - 1 <= n; ++i)
st[i][k] = smin(st[i][k - 1], st[i + (1 << k - 1)][k - 1]);
}
int query (int a, int b)
{
int k = lg[b - a + 1];
return smin(st[a][k], st[b - (1 << k) + 1][k]);
}
struct Data
{
int a, b, l, r;
Data (int _a, int _b, int _l, int _r) : a(_a), b(_b), l(_l), r(_r) {}
int calc () const { return s[r] - s[l - 1]; }
bool operator < (const Data &_) const { return calc() < _.calc(); }
};
int main ()
{
read(n, m, L, R);
for (int i = 1; i <= n; ++i)
read(s[i]), s[i] += s[i - 1];
init();
priority_queue <Data> q;
for (int i = 1; i + L - 1 <= n; ++i)
{
int t = min(i + R - 1, n);
q.emplace(i + L - 1, t, i, query(i + L - 1, t));
}
LL res = 0;
while (m--)
{
Data t = q.top(); q.pop();
res += t.calc();
if (t.r - 1 >= t.a)
q.emplace(t.a, t.r - 1, t.l, query(t.a, t.r - 1));
if (t.r + 1 <= t.b)
q.emplace(t.r + 1, t.b, t.l, query(t.r + 1, t.b));
}
write(res);
return 0;
}
|