0
1
mirror of https://git.sb/baoshuo/OI-codes.git synced 2024-11-08 13:18:46 +00:00

P3875 [TJOI2010]被污染的河流

https://www.luogu.com.cn/record/86620351
This commit is contained in:
Baoshuo Ren 2022-09-14 20:02:52 +08:00
parent c71610ef47
commit 9896659358
Signed by: baoshuo
GPG Key ID: 00CB9680AB29F51A

121
Luogu/P3875/P3875.cpp Normal file
View File

@ -0,0 +1,121 @@
#include <iostream>
#include <algorithm>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1e5 + 5;
int n, k;
long long ans;
std::vector<int> ys;
struct Segment {
int x, y1, y2, k;
Segment()
: x(0), y1(0), y2(0), k(0) {}
Segment(int _x, int _y1, int _y2, int _k)
: x(_x), y1(_y1), y2(_y2), k(_k) {}
bool operator<(const Segment& b) const {
return x < b.x;
}
};
struct node {
int l, r;
long long cnt, len;
node(const int& _l = 0, const int& _r = 0)
: l(_l), r(_r), cnt(0), len(0) {}
} tr[N << 2];
inline int find(int y) {
return std::lower_bound(ys.begin(), ys.end(), y) - ys.begin();
}
inline void pushup(int u) {
if (tr[u].cnt) {
tr[u].len = ys[tr[u].r + 1] - ys[tr[u].l];
} else if (tr[u].l != tr[u].r) {
tr[u].len = tr[u << 1].len + tr[u << 1 | 1].len;
} else {
tr[u].len = 0;
}
}
void build(int u, int l, int r) {
tr[u] = node(l, r);
if (l == r) return;
int mid = l + r >> 1;
build(u << 1, l, mid);
build(u << 1 | 1, mid + 1, r);
}
void modify(int u, int l, int r, int x) {
if (l <= tr[u].l && tr[u].r <= r) {
tr[u].cnt += x;
} else {
int mid = tr[u].l + tr[u].r >> 1;
if (l <= mid) modify(u << 1, l, r, x);
if (r > mid) modify(u << 1 | 1, l, r, x);
}
pushup(u);
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
std::vector<Segment> seg;
for (int i = 0; i < n; i++) {
int x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
if (x1 == x2) {
if (y1 > y2) std::swap(y1, y2);
x1--, x2++;
} else if (y1 == y2) {
if (x1 > x2) std::swap(x1, x2);
y1--, y2++;
}
seg.emplace_back(x1, y1, y2, 1);
seg.emplace_back(x2, y1, y2, -1);
ys.push_back(y1);
ys.push_back(y2);
}
std::sort(ys.begin(), ys.end());
ys.erase(std::unique(ys.begin(), ys.end()), ys.end());
build(1, 0, ys.size() - 2);
std::sort(seg.begin(), seg.end());
for (int i = 0; i < seg.size(); i++) {
if (i > 0) {
ans += tr[1].len * (seg[i].x - seg[i - 1].x);
}
modify(1, find(seg[i].y1), find(seg[i].y2) - 1, seg[i].k);
}
cout << ans << endl;
return 0;
}