46 lines
1.4 KiB
C++
46 lines
1.4 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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typedef long long LL;
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const int N = 200010;
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int n, a[N]; // n个元素，a[i]代表原始值
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LL big[N], small[N]; // big[i]:比a[i]大的元素个数，small[i]:比a[i]小的元素个数
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LL res1, res2; // V的个数，∧的个数
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// 树状数组模板
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typedef long long LL;
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#define lowbit(x) (x & -x)
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int c[N];
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void add(int x, int d) {
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for (int i = x; i < N; i += lowbit(i)) c[i] += d;
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}
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LL sum(int x) {
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LL res = 0;
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for (int i = x; i; i -= lowbit(i)) res += c[i];
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return res;
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}
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// 桶计数+前缀和
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int main() {
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scanf("%d", &n);
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for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
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for (int i = 1; i <= n; i++) { // 枚举每个点，由左到右一个个下场
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int x = a[i];
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small[i] = sum(x - 1); // 在我前面出场，并且，值比我小, 用于方便统计铁锹(∧)
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big[i] = sum(n) - sum(x - 1); // 在我前面出场，并且，值比我大, 用于方便统计尖刀(V)
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add(x, 1); // 以值为桶的标识，记录此桶中数量+1
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}
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memset(c, 0, sizeof c);
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for (int i = n; i; i--) {
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int x = a[i];
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res1 += small[i] * sum(x - 1);
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res2 += big[i] * (sum(n) - sum(x - 1));
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add(x, 1);
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}
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printf("%lld %lld\n", res2, res1);
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return 0;
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} |