BNU34067——Pair——————【找规律】

Pair

Time Limit: 1000ms

Memory Limit: 65536KB

64-bit integer IO format:  %lld      Java class name: Main

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 给出一个正整数N，从1到N这N个数中选出若干对pair，每个pair是1到N中不相等的两个数，1到N中每个数只能被选择一次，每个pair的值是它两个数的和，要求任意两个pair的值不相等，并且每个pair的值不超过N，问最多可以选出多少个pair。

 

Input

第一行为一个整数T，代表数据组数，T<=100。

接下来T行，每行一个正整数N，N<=100。

 

Output

对于每个输入N，输出最多可以选出多少对pair，每个输出占一行。

 

Sample Input

3

1

2

3

Sample Output

0

0

1

Hint

样例解释：

N=1时，不能选出两个数，所以为0；

N=2时，只能选出1和2组成一个pair，但是1+2=3>2，所以也为0；

N=3时，可以选择1和2组成一个pair，1+2=3<=3，可行，并且答案最大为1。

 

Source

2013年北京师范大学新生程序设计竞赛

 

 

解题思路：五个一循环。0 0 1 1 1。2 2 3 3 3 。4 4 5 5 5 。6 6 7 7 7 。

 

 

#include<bits/stdc++.h>

using namespace std;

int main(){

    int T;

    scanf("%d",&T);

    while(T--){

        int N;

        scanf("%d",&N);

        int n=N/5;

        int m=N%5;

        if(m==0){

            printf("%d\n",n*2-1);

        }else {

            n*=2;

            if(m>2)

                printf("%d\n",n+1);

            else{

                printf("%d\n",n);

            }

        }

    }

    return 0;

}