poj2301

Beat the Spread!

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 17794		Accepted: 8484

Description

Superbowl Sunday is nearly here. In order to pass the time waiting for the half-time commercials and wardrobe malfunctions, the local hackers have organized a betting pool on the game. Members place their bets on the sum of the two final scores, or on the absolute difference between the two scores. 
Given the winning numbers for each type of bet, can you deduce the final scores? 

Input

The first line of input contains n, the number of test cases. n lines follow, each representing a test case. Each test case gives s and d, non-negative integers representing the sum and (absolute) difference between the two final scores.

Output

For each test case, output a line giving the two final scores, largest first. If there are no such scores, output a line containing "impossible". Recall that football scores are always non-negative integers.

Sample Input

2
40 20
20 40

Sample Output

30 10
impossible

Source

Waterloo local 2005.02.05

水题，唯一要注意的就是x和y如果一个是偶数一个是奇数也应该impossible，这题在今年的中国地质大学邀请赛上面有一个类似的，不过那个难多了。需要二分

#include<iostream>
#include<cstdio>
using namespace std;

int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        int x,y;
        for(int i=0 ;i<n;i++)
        {
            scanf("%d%d",&x,&y);
            if(x<y||x%2==0&&y%2!=0||x%2!=0&&y%2==0)
                printf("impossible
");
            else
            {
                int larger = (x+y)/2;
                int litter = x-larger;
                printf("%d %d
",larger,litter);
            }
        }
    }
    return 0;
}