# [BZOJ1651][Usaco2006 Feb]Stall Reservations 专用牛棚

## 1651: [Usaco2006 Feb]Stall Reservations 专用牛棚

Time Limit: 10 Sec  Memory Limit: 64 MB Submit: 990  Solved: 568 [Submit][Status][Discuss]

## Description

Oh those picky N (1 <= N <= 50,000) cows! They are so picky that each one will only be milked over some precise time interval A..B (1 <= A <= B <= 1,000,000), which includes both times A and B.  Obviously, FJ must create a reservation system to determine which stall each cow can be assigned for her milking time. Of course, no cow will share such a private moment with other cows.  Help FJ by determining: * The minimum number of stalls required in the barn so that each   cow can have her private milking period * An assignment of cows to these stalls over time

## Input

* Line 1: A single integer, N

* Lines 2..N+1: Line i+1 describes cow i's milking interval with two         space-separated integers.

## Output

* Line 1: The minimum number of stalls the barn must have.

* Lines 2..N+1: Line i+1 describes the stall to which cow i will be         assigned for her milking period.

5
1 10
2 4
3 6
5 8
4 7

## Sample Output

4

OUTPUT DETAILS:

Here's a graphical schedule for this output:

Time     1  2  3  4  5  6  7  8  9 10
Stall 1 c1>>>>>>>>>>>>>>>>>>>>>>>>>>>
Stall 2 .. c2>>>>>> c4>>>>>>>>> .. ..
Stall 3 .. .. c3>>>>>>>>> .. .. .. ..
Stall 4 .. .. .. c5>>>>>>>>> .. .. ..

Other outputs using the same number of stalls are possible.

#include <cstdio>
int n = 0;
char ch = getchar();
while(ch < '0' || ch > '9') ch = getchar();
while(ch <= '9' && ch >= '0'){
n = (n << 1) + (n << 3) + ch - '0';
ch = getchar();
}
return n;
}
template <typename _Tp>
inline _Tp max_(const _Tp &a, const _Tp &b){
return a > b ? a : b;
}
int cnt[1000001] = {0}, n;
int main(){
int r = 0;
for(int s, t, i = 1; i <= n; i++){
cnt[s] ++;
cnt[t + 1] --;
r = max_(r, t);
}
int sum = 0, ans = 0;
for(int i = 1; i <= r; i++){
sum += cnt[i];
ans = max_(ans, sum);
}
printf("%d\n", ans);
return 0;
}

posted @ 2017-09-11 18:07  Elder_Giang  阅读(90)  评论(0编辑  收藏  举报