OpenJudge

1089:Intervals

总时间限制:
1000ms
内存限制:
65536kB
描述
There is given the series of n closed intervals [ai; b i], where i=1,2,...,n. The sum of those intervals may berepresented as a sum of closed pairwise non−intersecting intervals. The task is to find such representation with the minimal number of intervals. The intervals of this representation should be written in the output file in acceding order. We say that the intervals [a; b] and [c; d] are in ascending order if, and only if a <= b < c <= d.
Task
Write a program which:
.reads from the std input the description of the series of intervals,
.computes pairwise non−intersecting intervals satisfying the conditions given above,
.writes the computed intervals in ascending order into std output
输入
In the first line of input there is one integer n, 3 <= n <= 50000. This is the number of intervals. In the (i+1)−st line, 1 <= i <= n, there is a description of the interval [ai; bi] in the form of two integers ai and bi separated by a single space, which are respectively the beginning and the end of the interval,1 <= ai <= bi <= 1000000.
输出
The output should contain descriptions of all computed pairwise non−intersecting intervals. In each line should be written a description of one interval. It should be composed of two integers, separated by a single space, the beginning and the end of the interval respectively. The intervals should be written into the output in ascending order.
样例输入
5
5 6
1 4
10 10
6 9
8 10
样例输出
1 4
5 10
来源
POI VIII Stage 1 Problem 2
全局题号
91
添加于
2009-10-29
提交次数
578
尝试人数
181
通过人数
148
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