Stall Reservations

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

Many answers are correct for each test dataset; a program will grade your answer.

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

Sample Output

Hint

Explanation of the sample:

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.

poj链接： http://poj.org/problem?id=3190

代码：

#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;
struct node
{
    int x,y,ord,put;
    friend bool operator < (const node a,const node b)
    {
        if(a.y==b.y)
            return a.x>b.x;
        return a.y>b.y;
    }
};
int cmp(struct node a,struct node b)
{
    if(a.x==b.x)
        return a.y<b.y;
    return a.x<b.x;
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        int i,ans[50010]= {0},d=1;
        struct node s[50010];
        priority_queue <node> q;
        for(i=0; i<n; i++)
        {
            scanf("%d%d",&s[i].x,&s[i].y);
            s[i].ord=i;
        }
        sort(s,s+n,cmp);
        q.push(s[0]);
        ans[q.top().ord]=d;
        for(i=1; i<n; i++)
        {
            if( s[i].x>q.top().y)
            {
                ans[s[i].ord]=ans[q.top().ord];
                q.pop();
            }
            else
            {
                d++;
                ans[s[i].ord]=d;
            }
            q.push(s[i]);
        }
        printf("%d
",d);
        for(i=0; i<n; i++)
            printf("%d
",ans[i]);
    }
    return 0;
}