# POJ3190 Stall Resevrations

## 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.

• 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.

## Hint

Explanation of the sample:

Other outputs using the same number of stalls are possible.

Other outputs using the same number of stalls are possible.

## Analysis

1. 每头奶牛有自己的产奶时间区间，现在要建一批牛栏，使得每个牛都能独自在牛栏里产奶，求最少牛栏数和牛与牛栏的分配关系。
2. 将牛按开始时间排序，最小堆维护每个牛栏最右端点的值，对每个牛，若其开始时间大于堆顶，则放入此牛栏，否则新建牛栏。
# POJ