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Posted 2020-09-30 __AiR_H

1 HDU 5091 Beam Cannon

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #include <queue>
 7 #include <vector>
 8 #include <stack>
 9 #include <map>
10 #include <set>
11 #include <cmath>
12 #include <cctype>
13 #include <ctime>
14 
15 using namespace std;
16 
17 #define REP(i, n) for (int i = 0; i < (n); ++i)
18 #define eps 1e-9
19 #define lc id << 1
20 #define rc id << 1 | 1
21 #define lson low, mid, lc
22 #define rson mid + 1, high, rc
23 
24 struct Node {
25     int x, y1, y2, flag;
26     bool operator < (const Node& a) const {
27         if (x == a.x) { return flag > a.flag; } return x < a.x;
28     }
29 };
30 
31 typedef long long ll;
32 typedef pair<int, int> pii;
33 
34 const int INF = 0x7fffffff;
35 const int maxn = 1e5 + 10;
36 int n, h, w, Size, x, y;
37 Node node[maxn];
38 vector<int> v;
39 int Max[maxn * 4], lazy[maxn * 4];
40 
41 int get_id(int a) { return lower_bound(v.begin(), v.end(), a) - v.begin() + 1; }
42 void build(int low, int high, int id) {
43     Max[id] = lazy[id] = 0; if (low == high) { return; }
44     int mid = (low + high) / 2; build(lson); build(rson);
45 }
46 inline void push_up(int id) { Max[id] = max(Max[lc], Max[rc]); }
47 inline void push_down(int id) {
48     if (!lazy[id]) { return; }
49     lazy[lc] += lazy[id]; Max[lc] += lazy[id];
50     lazy[rc] += lazy[id]; Max[rc] += lazy[id];
51     lazy[id] = 0;
52 }
53 void update(int l, int r, int key, int low, int high, int id) {
54     if (l == low && r == high) {
55         lazy[id] += key; Max[id] += key; return;
56     }
57     int mid = (low + high) / 2; push_down(id);
58     if (r <= mid) { update(l, r, key, lson); }
59     else if (l >= mid + 1) { update(l, r, key, rson); }
60     else { update(l, mid, key, lson); update(mid + 1, r, key, rson); }
61     push_up(id);
62 }
63 
64 int main() {
65 #ifdef __AiR_H
66     freopen("in.txt", "r", stdin);
67 //    freopen("out.txt", "w", stdout);
68 #endif // __AiR_H
69     while (scanf("%d", &n) && n >= 0) {
70 //        printf("n = %d\n", n);
71         scanf("%d %d", &w, &h); v.clear();
72         for (int i = 0; i < n; ++i) {
73             scanf("%d %d", &x, &y);
74             node[i * 2] = Node{x, y - h, y, 1};
75             node[i * 2 + 1] = Node{x + w, y - h, y, -1};
76             v.push_back(y - h); v.push_back(y);
77         }
78         sort(v.begin(), v.end()); v.erase(unique(v.begin(), v.end()), v.end());
79         n *= 2; sort(node, node + n); Size = v.size(); build(1, Size, 1);
80         int id1, id2, ans = 0;
81         for (int i = 0; i < n; ++i) {
82             id1 = get_id(node[i].y1); id2 = get_id(node[i].y2);
83             update(id1, id2, node[i].flag, 1, Size, 1);
84             ans = max(ans, Max[1]);
85         }
86         printf("%d\n", ans);
87     }
88 #ifdef __AiR_H
89     printf("Time used = %.2fs\n", (double)clock() / CLOCKS_PER_SEC);
90 #endif // __AiR_H
91     return 0;
92 }

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