Kirai[CF816B] Karen and Coffee（前缀和，思维）
题目链接：http://codeforces.com/contest/816/problem/B
题意：一个大区间被n条线覆盖，接下来有q次询问，询问[l,r]内有多少个点被>=k个线覆盖。
区间两头左闭右开打标记，左边+1右边-1，维护这个标记的前缀和，再维护一个前缀和，找到上一个前缀和里>=k的点，更新到当前的前缀和里就是了。
1 #include <algorithm> 2 #include <iostream> 3 #include <iomanip> 4 #include <cstring> 5 #include <climits> 6 #include <complex> 7 #include <cassert> 8 #include <cstdio> 9 #include <bitset> 10 #include <vector> 11 #include <deque> 12 #include <queue> 13 #include <stack> 14 #include <ctime> 15 #include <set> 16 #include <map> 17 #include <cmath> 18 using namespace std; 19 #define fr first 20 #define sc second 21 #define cl clear 22 #define BUG puts("here!!!") 23 #define W(a) while(a--) 24 #define pb(a) push_back(a) 25 #define Rint(a) scanf("%d", &a) 26 #define Rll(a) scanf("%lld", &a) 27 #define Rs(a) scanf("%s", a) 28 #define Cin(a) cin >> a 29 #define FRead() freopen("in", "r", stdin) 30 #define FWrite() freopen("out", "w", stdout) 31 #define Rep(i, len) for(int i = 0; i < (len); i++) 32 #define For(i, a, len) for(int i = (a); i < (len); i++) 33 #define Cls(a) memset((a), 0, sizeof(a)) 34 #define Clr(a, x) memset((a), (x), sizeof(a)) 35 #define Full(a) memset((a), 0x7f7f7f, sizeof(a)) 36 #define lrt rt << 1 37 #define rrt rt << 1 | 1 38 #define pi 3.14159265359 39 #define RT return 40 #define lowbit(x) x & (-x) 41 #define onenum(x) __builtin_popcount(x) 42 typedef long long LL; 43 typedef long double LD; 44 typedef unsigned long long ULL; 45 typedef pair<int, int> pii; 46 typedef pair<string, int> psi; 47 typedef pair<LL, LL> pll; 48 typedef map<string, int> msi; 49 typedef vector<int> vi; 50 typedef vector<LL> vl; 51 typedef vector<vl> vvl; 52 typedef vector<bool> vb; 53 54 const int maxn = 200200; 55 int n, k, q; 56 int line[maxn]; 57 int sum[maxn]; 58 59 signed main() { 60 // FRead(); 61 int x, y; 62 while(~Rint(n)) { 63 Rint(k); Rint(q); 64 Cls(line); Cls(sum); 65 Rep(i, n) { 66 Rint(x); Rint(y); 67 line[x]++; line[y+1]--; 68 } 69 For(i, 1, 200020) { 70 line[i] += line[i-1]; 71 if(line[i] >= k) sum[i] = sum[i-1] + 1; 72 else sum[i] = sum[i-1]; 73 } 74 W(q) { 75 Rint(x); Rint(y); 76 printf("%d\n", sum[y]-sum[x-1]); 77 } 78 } 79 RT 0; 80 }
