[BZOJ] 1651: [Usaco2006 Feb]Stall Reservations 专用牛棚
1651: [Usaco2006 Feb]Stall Reservations 专用牛棚
Time Limit: 10 Sec Memory Limit: 64 MBSubmit: 987 Solved: 566
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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
有N头牛,每头牛有个喝水时间,这段时间它将专用一个Stall 现在给出每头牛的喝水时间段,问至少要多少个Stall才能满足它们的要求
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.
Sample Input
1 10
2 4
3 6
5 8
4 7
Sample Output
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.
HINT
不妨试下这个数据,对于按结束点SORT,再GREEDY的做法 1 3 5 7 6 9 10 11 8 12 4 13 正确的输出应该是3
Source
Analysis
求区间叠加最大数,经典的差分老题
然而第一次提交的时候因为是扫描 1-n 不知道为什么被卡了
后来改成了 1-最远区间右端点 就过了
很迷
Code
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include<cstdio> 2 #include<iostream> 3 using namespace std; 4 5 int r,cnt[10000000],ret,cncct,a,b,n; 6 7 int main(){ 8 scanf("%d",&n); 9 10 for(int i = 1;i <= n;i++){ 11 scanf("%d %d",&a,&b); 12 cnt[a]++,cnt[b+1]--; 13 r = max(r,b); 14 } 15 16 int cncct = 0,ret = 0; 17 for(int i = 1;i <= r;i++){ 18 cncct += cnt[i]; 19 ret = max(ret,cncct); 20 } 21 22 printf("%d",ret); 23 24 return 0; 25 }