[51nod 1208] Stars in Your Window（线段树，扫描线）

题目链接：https://www.51nod.com/onlineJudge/questionCode.html#!problemId=1208

题意：也是矩形框点问题，不过每个点有权值，希望权值最大。

直接把出入的event中的sign变成对应权值，更新到线段树上就行了。

#include <bits/stdc++.h>
using namespace std;

#define lrt rt << 1
#define rrt rt << 1 | 1
typedef struct Seg {
    int add, val;
}Seg;
typedef struct Event {
    int l, r, h, val;
}Event;
const int maxn = 100500;
Seg seg[maxn<<4];
vector<Event> event;
int hh[maxn<<1], hcnt;
int n, w, h;

bool cmp(Event a, Event b) {
    if(a.h != b.h) return a.h < b.h;
    return a.val > b.val;
}

void build(int l, int r, int rt) {
    seg[rt].val = seg[rt].add = 0;
    if(l == r) return;
    int mid = (l + r) >> 1;
    build(l, mid, lrt);
    build(mid+1, r, rrt);
}


void pushup(int rt) {
    seg[rt].val = max(seg[lrt].val, seg[rrt].val);
}

void pushdown(int rt) {
    if(seg[rt].add) {
        seg[lrt].add += seg[rt].add;
        seg[rrt].add += seg[rt].add;
        seg[lrt].val += seg[rt].add;
        seg[rrt].val += seg[rt].add;
        seg[rt].add = 0;
    }
}

void update(int L, int R, int val, int l, int r, int rt) {
    if(L <= l && r <= R) {
        seg[rt].add += val;
        seg[rt].val += val;
        return;
    }
    pushdown(rt);
    int mid = (l + r) >> 1;
    if(L <= mid) update(L, R, val, l, mid, lrt);
    if(mid < R) update(L, R, val, mid+1, r, rrt);
    pushup(rt);
}

int id(int x) {
    return lower_bound(hh, hh+hcnt, x) - hh + 1;
}

int main() {
    // freopen("in", "r", stdin);
    int x, y, v;
    while(~scanf("%d%d%d",&n,&w,&h)) {
        event.clear(); hcnt = 0;
        for(int i = 0; i < n; i++) {
            scanf("%d%d%d",&x,&y,&v);
            event.push_back(Event{x, x+w, y, v});
            event.push_back(Event{x, x+w, y+h, -v});
            hh[hcnt++] = x; hh[hcnt++] = x + w;
        }
        sort(event.begin(), event.end(), cmp);
        sort(hh, hh+hcnt); hcnt = unique(hh, hh+hcnt) - hh;
        build(1, hcnt, 1);
        int ret = 0;
        for(int i = 0; i < event.size(); i++) {
            int l = id(event[i].l);
            int r = id(event[i].r);
            int val = event[i].val;
            update(l, r, val, 1, hcnt, 1);
            ret = max(ret, seg[1].val);
        }
        printf("%d
", ret);
    }
    return 0;
}