蓝桥杯 小朋友排队+

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {
static int[] old;
static int[] now;
static int[] treearray;
static int[] left;
static int[] right;
static int[] hight;
static int a;

// static int n;
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
a = sc.nextInt();
old = new int[a + 1];
now = new int[a + 1];
treearray = new int[a + 1];
for (int i = 1; i < old.length; i++) {
now[i] = old[i] = sc.nextInt();
}
//
Arrays.sort(old);
int k = 1;
Map<Integer, Integer> hs = new HashMap<Integer, Integer>();
for (int i = 1; i < old.length; i++) {
hs.put(old[i], k++);
}
for (int i = 1; i < now.length; i++) {
now[i] = hs.get(now[i]);
}
//
left = new int[a + 1];

for (int i = 1; i <= a; i++) {
update(now[i], 1);
left[i] = i - getSum(now[i]);
}
// sop(left);
//
right = new int[a + 1];
treearray = new int[a + 1];
for (int f = a; f >= 1; f--) {
update(now[f], 1);
right[f] = getSum(now[f] - 1);
}
// sop(right);

//
hight = new int[a + 1];
for (int i = 1; i <= a; i++) {
hight[i] = left[i] + right[i];
}
long ans = 0;
for (int i = 1; i <= a; i++) {
ans += (1 + hight[i]) * hight[i] / 2;
}
System.out.println(ans);

}

public static void update(int t, int x) {
for (int i = t; i < a + 1; i += lowbit(i)) {
treearray[i] += x;
}
}

public static int getSum(int x) {
int temp = 0;
for (int j = x; j >= 1; j -= lowbit(j)) {
temp += treearray[j];
}
return temp;
}

private static int lowbit(int x) {
// TODO Auto-generated method stub
return x & -x;
}
}