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241. 楼兰图腾
https://www.acwing.com/problem/content/submission/code_detail/13302049/
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AcWing/241/241.cpp
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52
AcWing/241/241.cpp
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#include <iostream>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 2e5 + 5;
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int n, y[N], l[N], r[N], c1[N], c2[N];
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long long ans1, ans2;
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inline int lowbit(int x) {
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return x & -x;
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}
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void add(int *c, int x, int y) {
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for (; x <= n; x += lowbit(x)) c[x] += y;
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}
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int sum(int *c, int x) {
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int ans = 0;
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for (; x; x -= lowbit(x)) ans += c[x];
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return ans;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin >> n;
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for (int i = 1; i <= n; i++) {
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cin >> y[i];
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}
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for (int i = 1; i <= n; i++) {
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l[i] = sum(c1, y[i] - 1);
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add(c1, y[i], 1);
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}
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for (int i = n; i; i--) {
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r[i] = sum(c2, y[i] - 1);
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add(c2, y[i], 1);
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}
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for (int i = 1; i <= n; i++) {
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ans1 += 1ll * (i - 1 - l[i]) * (n - i - r[i]);
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ans2 += 1ll * l[i] * r[i];
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}
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cout << ans1 << ' ' << ans2 << endl;
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return 0;
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}
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