提交时间:2025-02-07 20:20:27

运行 ID: 36158

#include<bits/stdc++.h> using namespace std; const int N = 10000; int f[N], w[N], sum[2 * N], n; long long ans; int main() { scanf("%d", &n); for (int i = 0; i < n; i++) { int x; scanf("%d", &x); f[i] = 1; w[x - 1] = i; } for (int i = 0; i < n; i++) { f[w[i]] = 0; memset(sum, 0, sizeof sum); sum[n] = 1; int p = n; for (int j = 0; j < w[i]; j++) { p += f[j]; sum[p] += j + 2; } long long s = 0; for (int j = w[i]; j < n; j++) { p += f[j]; s += sum[p] * 1ll * (j + 1); } ans += s * (i + 1); f[w[i]] = -1; } printf("%lld\n", ans); return 0; }