【BZOJ1367】【Baltic2004】sequence

#include<bits/stdc++.h>
using namespace std;
#define MAXN	1000005
struct Node {
int value, father, size;
int child[2], depth[2];
};
Node a[MAXN];
int n, top, Stack[MAXN];
int x[MAXN], y[MAXN], size[MAXN], value[MAXN];
int merge(int x, int y) {
if (x == 0) return y;
if (y == 0) return x;
if (a[x].value < a[y].value) swap(x, y);
a[x].size += a[y].size;
a[x].child[1] = merge(a[x].child[1], y);
a[a[x].child[1]].father = x;
a[x].depth[1] = 1 + max(a[a[x].depth[1]].child[0], a[a[x].child[1]].depth[1]);
if (a[x].depth[1] > a[x].child[0]) {
swap(a[x].depth[0], a[x].depth[1]);
swap(a[x].child[0], a[x].child[1]);
}
return x;
}
int del(int x) {
int tmp = merge(a[x].child[1], a[x].child[0]);
a[tmp].father = 0;
return tmp;
}
int main() {
scanf("%d", &n);
for (int i = 1; i <= n; i++) {
scanf("%d", &a[i].value);
a[i].value -= i;
a[i].size = 1;
}
for (int i = 1; i <= n; i++) {
Stack[++top] = i;
value[top] = a[i].value;
size[top] = 1;
x[top] = i; y[top] = i;
while (top > 1 && value[top] < value[top - 1]) {
top--;
Stack[top] = merge(Stack[top], Stack[top + 1]);
size[top] += size[top + 1];
y[top] = y[top + 1];
while (a[Stack[top]].size > (size[top] + 1) / 2)
Stack[top] = del(Stack[top]);
value[top] = a[Stack[top]].value;
}
}
long long ans = 0;
for (int i = 1; i <= top; i++)
for (int j = x[i]; j <= y[i]; j++)
ans += abs(value[i] - a[j].value);
printf("%lld\n", ans);
return 0;
}