BZOJ3888 [Usaco2015 Jan]Stampede

  1 /**************************************************************
  2     Problem: 3888
  3     User: rausen
  4     Language: C++
  5     Result: Accepted
  6     Time:1204 ms
  7     Memory:22684 kb
  8 ****************************************************************/
  9  
 10 #include <cstdio>
 11 #include <algorithm>
 12  
 13 using namespace std;
 14 const int N = 1e5 + 5;
 15  
 16 struct data {
 17     int x, y, c;
 18     int st, ed;
 19      
 20     inline void read() {
 21         scanf("%d%d%d", &x, &y, &c);
 22         x *= -1, st = c * (x - 1), ed = st + c;
 23     }
 24      
 25     inline bool operator < (const data &p) const {
 26         return y > p.y;
 27     }
 28 } a[N];
 29  
 30 struct seg_node {
 31     seg_node *ls, *rs;
 32     int v;
 33 } *seg_null, *seg_root, mempool[N << 4], *cnt_seg = mempool;
 34  
 35 int n, ans;
 36 int v[N];
 37 int t[N << 1], tot;
 38  
 39 #define Ls p -> ls
 40 #define Rs p -> rs
 41 #define V p -> v
 42 #define mid (l + r >> 1)
 43 inline void seg_get_null(seg_node *&p) {
 44     p = cnt_seg, Ls = Rs = p;
 45 }
 46  
 47 inline void seg_new(seg_node *&p) {
 48     p = ++cnt_seg, *p = *seg_null;
 49 }
 50  
 51 inline void seg_push(seg_node *p) {
 52     if (V) {
 53         Ls -> v = Rs -> v = V;
 54         V = 0;
 55     }
 56 }
 57  
 58 inline void seg_build(seg_node *&p, int l, int r) {
 59     seg_new(p);
 60     if (l == r) return;
 61     seg_build(Ls, l, mid), seg_build(Rs, mid + 1, r);
 62 }
 63  
 64 inline void seg_modify(seg_node *p, int l, int r, int L, int R, int v) {
 65     if (L <= l && r <= R) {
 66         V = v;
 67         return;
 68     }
 69     seg_push(p);
 70     if (L <= mid) seg_modify(Ls, l, mid, L, R, v);
 71     if (mid < R) seg_modify(Rs, mid + 1, r, L, R, v);
 72 }
 73  
 74 inline int seg_query(seg_node *p, int l, int r, int pos) {
 75     if (l == r) return V;
 76     seg_push(p);
 77     if (pos <= mid) return seg_query(Ls, l, mid, pos);
 78     else return seg_query(Rs, mid + 1, r, pos);
 79 }
 80 #undef Ls
 81 #undef Rs
 82 #undef V
 83 #undef mid
 84  
 85 int main() {
 86     int i;
 87     scanf("%d", &n);
 88     for (i = 1; i <= n; ++i)
 89         a[i].read();
 90     sort(a + 1, a + n + 1);
 91     for (i = 1; i <= n; ++i) 
 92         t[i * 2 - 1] = a[i].st, t[i * 2] = a[i].ed;
 93     sort(t + 1, t + 2 * n + 1);
 94     tot = unique(t + 1, t + 2 * n + 1) - t;
 95     for (i = 1; i <= n; ++i) {
 96         a[i].st = lower_bound(t + 1, t + tot + 1, a[i].st) - t;
 97         a[i].ed = lower_bound(t + 1, t + tot + 1, a[i].ed) - t;
 98         a[i].st *= 2, a[i].ed *= 2;
 99     }
100     tot *= 2;
101     seg_get_null(seg_null);
102     seg_build(seg_root = seg_null, 1, tot);
103     for (i = 1; i <= n; ++i)
104         seg_modify(seg_root, 1, tot, a[i].st, a[i].ed, i);
105     for (i = 1; i <= tot; ++i)
106         v[seg_query(seg_root, 1, tot, i)] = 1;
107     for (ans = 0, i = 1; i <= n; ++i)
108         ans += v[i];
109     printf("%d\n", ans);
110     return 0;
111 }