[HIHO1079]离散化（线段树、染色）

题目链接：http://hihocoder.com/problemset/problem/1079

MD坑爹，线段查询的时候左闭右开。插完挨个点找一遍扔set里，注意没染色的情况。

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

 #define lson l, m, rt << 1
 #define rson m + 1, r, rt << 1 | 1
 const int maxn = ;
 int sum[maxn<<];

 void pushDOWN(int rt) {
     if(sum[rt] != -) {
         sum[rt<<] = sum[rt<<|] = sum[rt];
         sum[rt] = -;
     }
 }

 void update(int L, int R, int c, int l, int r, int rt) {
     if(L <= l && r <= R) {
         sum[rt] = c;
         return;
     }
     pushDOWN(rt);
     int m = (l + r) >> ;
     if(L <= m) update(L, R, c, lson);
     if(R > m) update(L, R, c, rson);
 }

 int query(int p, int l, int r, int rt) {
     if(l == r) return sum[rt];
     pushDOWN(rt);
     int m = (l + r) >> ;
     if(p <= m) return query(p, lson);
     else return query(p, rson);
 }

 int h[maxn], hcnt;
 int n, m;
 int lo[maxn], hi[maxn];

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

 int main() {
     // freopen("in", "r", stdin);
     while(~scanf("%d%d",&n,&m)) {
         hcnt = ;
         memset(sum, -, sizeof(sum));
         for(int i = ; i < n; i++) {
             scanf("%d%d",&lo[i], &hi[i]);
             h[hcnt++] = lo[i], h[hcnt++] = hi[i];
         }
         sort(h, h+hcnt); hcnt = unique(h, h+hcnt) - h;
         m = hcnt;
         for(int i = ; i < n; i++) {
             update(id(lo[i]), id(hi[i])-, i, , m, );
         }
         set<int> s;
         s.insert(-);
         for(int i = ; i <= m; i++) {
             s.insert(query(i, , m, ));
             // printf("%d ", query(i, 1, m, 1));
         }
         // printf("\n");
         printf("%d\n", s.size()-);
     }
     return ;
 }