Problem:
Score : 400 points

Problem Statement

One day, Snuke was given a permutation of length N, a_1, a_2, ..., a_N, from his friend.

Find the following:

Constraints

1 ≦ N ≦ 200,000

(a_1, a_2, ..., a_N) is a permutation of (1, 2, ..., N).

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the answer.

Note that the answer may not fit into a 32-bit integer.

Sample Input 1

3
2 1 3

Sample Output 1

9

Sample Input 2

4
1 3 2 4

Sample Output 2

19

Sample Input 3

8
5 4 8 1 2 6 7 3

Sample Output 3

85

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<iostream>
#include<iostream>
#include<stdio.h>
#include<string>
#include<vector>
#include<map>
#include<math.h>
#include<algorithm>
#include<iomanip>

using namespace std;

int n;
unsigned long long ans = 0;
vector<int> a, b, l, r;


int main() {
	cin >> n;
	a.resize(n);
	b.resize(n);
	l.resize(n);
	r.resize(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
		b[a[i] - 1] = i;
	}
	for (int i = n - 1; i >= 0; i--) {
		bool rcheck = false;
		if (b[i] + 1 < n) {
			if (r[b[i] + 1] > 0) {
				r[b[i]] = r[b[i] + 1] + 1;
				rcheck = true;
			}
			else
				r[b[i]] = 1;
		}
		else {
			r[b[i]] = 1;
		}
		if (b[i] - 1 >= 0) {
			if (l[b[i] - 1] > 0) {
				l[b[i]] = l[b[i] - 1] + 1;
			}
			else
				l[b[i]] = 1;
		}
		else {
			l[b[i]] = 1;
		}
		if (b[i] + 1 < n) {
			if (r[b[i] + 1] > 0) {
				l[b[i] + r[b[i] + 1]] += l[b[i]];
			}
		}
		if (b[i] - 1 >= 0) {
			if (l[b[i] - 1] > 0) {
				r[b[i] - l[b[i] - 1]] += r[b[i]];
			}
		}
		ans += (i + 1) * l[b[i]] * r[b[i]];
	}
	cout << ans << endl;

//	cin >> n;

	return 0;
}