OpenJudge

2:Pearl Pairing

总时间限制:
10000ms
单个测试点时间限制:
1000ms
内存限制:
65536kB
描述
At Bessie's recent birthday party, she received N (2 <= N <= 100,000; N%2 == 0) pearls, each painted one of C different colors (1 <= C <= N).

Upon observing that the number of pearls N is always even, her creative juices flowed and she decided to pair the pearls so that each pair of pearls has two different colors.

Knowing that such a set of pairings is always possible for the supplied testcases, help Bessie perform such a pairing. If there are multiple ways of creating a pairing, any solution suffices.
输入
* Line 1: Two space-separated integers: N and C

* Lines 2..C + 1: Line i+1 tells the count of pearls with color i: C_i
输出
* Lines 1..N/2: Line i contains two integers a_i and b_i indicating that Bessie can pair two pearls with respective colors a_i and b_i.
样例输入
8 3
2
2
4
样例输出
1 3
1 3
2 3
3 2
提示
INPUT DETAILS:

There are 8 pearls and 3 different colors. Two pearls have color I; two have color II; four have color III.

OUTPUT DETAILS:

Bessie pairs each pearl of color III with one of color I and II.
来源
USACO March 2008 Gold
全局题号
2390
提交次数
18
尝试人数
8
通过人数
4