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https://git.sb/baoshuo/OI-codes.git
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113 lines
2.2 KiB
C++
113 lines
2.2 KiB
C++
#include <iostream>
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#include <algorithm>
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#include <limits>
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#include <utility>
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#include <vector>
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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, c[N], st[N];
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long long ans;
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std::vector<int> xs;
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std::pair<int, int> p[N];
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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 insert(int x, int y) {
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for (; x; x -= lowbit(x)) c[x] = std::min(c[x], y);
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}
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int query(int x) {
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int res = std::numeric_limits<int>::max();
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for (; x <= n; x += lowbit(x)) res = std::min(res, c[x]);
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return res;
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}
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void clear(int x) {
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for (; x; x -= lowbit(x)) c[x] = std::numeric_limits<int>::max();
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}
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int search(int l, int r, int y) {
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int res = r + 1;
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while (l <= r) {
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int mid = l + r >> 1;
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if (p[st[mid]].second < y) {
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res = mid;
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r = mid - 1;
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} else {
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l = mid + 1;
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}
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}
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return res;
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}
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void solve(int l, int r) {
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if (l >= r) return;
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int mid = (l + r) >> 1;
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solve(l, mid);
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solve(mid + 1, r);
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for (int i = l, j = mid + 1, top = 0; i <= mid; i++) {
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while (j <= r && p[j].second > p[i].second) {
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while (top && p[st[top]].first > p[j].first) top--;
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st[++top] = j++;
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}
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ans += top - search(1, top, query(p[i].first)) + 1;
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insert(p[i].first, p[i].second);
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}
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for (int i = l; i <= mid; i++) {
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clear(p[i].first);
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}
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std::sort(p + l, p + r + 1, [](const std::pair<int, int> &a, const std::pair<int, int> &b) {
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return a.second > b.second;
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});
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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.tie(nullptr);
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std::fill_n(c, N, std::numeric_limits<int>::max());
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cin >> n;
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for (int i = 1; i <= n; i++) {
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cin >> p[i].first >> p[i].second;
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xs.emplace_back(p[i].first);
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}
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std::sort(p + 1, p + 1 + n, [](const std::pair<int, int> &a, const std::pair<int, int> &b) {
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return a.first < b.first;
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});
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std::sort(xs.begin(), xs.end());
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xs.erase(std::unique(xs.begin(), xs.end()), xs.end());
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for (int i = 1; i <= n; i++) {
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p[i].first = std::lower_bound(xs.begin(), xs.end(), p[i].first) - xs.begin() + 1;
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}
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solve(1, n);
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cout << ans << endl;
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return 0;
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}
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