POJ 2481 Cows

  • 2018-07-23
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Farmer John’s cows have discovered that the clover growing along the ridge of the hill (which we can think of as a one-dimensional number line) in his field is particularly good.

Farmer John has N cows (we number the cows from 1 to N). Each of Farmer John’s N cows has a range of clover that she particularly likes (these ranges might overlap). The ranges are defined by a closed interval [S,E].

But some cows are strong and some are weak. Given two cows: cowi and cowj, their favourite clover range is [Si, Ei] and [Sj, Ej]. If Si <= Sj and Ej <= Ei and Ei – Si > Ej – Sj, we say that cowi is stronger than cowj.

For each cow, how many cows are stronger than her? Farmer John needs your help!


The input contains multiple test cases.

For each test case, the first line is an integer N (1 <= N <= 105), which is the number of cows. Then come N lines, the i-th of which contains two integers: S and E(0 <= S < E <= 105) specifying the start end location respectively of a range preferred by some cow. Locations are given as distance from the start of the ridge.

The end of the input contains a single 0.


For each test case, output one line containing n space-separated integers, the i-th of which specifying the number of cows that are stronger than cowi.

Sample Input:

1 2
0 3
3 4

Sample Output:

1 0 0


树状数组,将牛的S值看做坐标系上的横坐标x,E值看做坐标系上的纵坐标y,所要求的就是每个点左上方有多少个点(Ei – Si > Ej – Sj表示E和S同时相等不算),这么转换着理解就和HDU 1541、POJ 2352很像,不过需要先排序。

HDU 1541 POJ 2352 Stars