HDU杭电5630 ( Rikka with Chess )

http://acm.hdu.edu.cn/showproblem.php?pid=5630

Rikka with Chess

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 516    Accepted Submission(s): 430

Problem Description

Yuta gives Rikka a chess board of size n×m.

As we all know, on a chess board, every cell is either black or white and every two cells that share a side have different colors.

Rikka can choose any rectangle formed by board squares and perform an inversion, every white cell becomes black, and vice versa.

Rikka wants to turn all cells into the same color, please tell Rikka the minimal number of inversions she need to achieve her goal.

 

Input

The first line contains a number T(T≤10) ——The number of the testcases.

Each testcase contains two numbers n,m(n≤109,m≤109).

 

Output

For each testcase, print a single number which represents the answer.

 

Sample Input

31 22 23 3

 

Sample Output

122

 

题意：棋盘上是黑白交替的棋子，对某行或者某列处理，问最少多少次能把棋盘上的元素变成一种颜色

举个例子吧：

4*4的棋盘，你先对第二行第四行处理，然后对第二列第四列处理，你会发现解决了，就是这个规律，自己可以试试，这里不方面画图

#include <cstdio>#include <cstring>#include <algorithm>#define max(a,b) (a>b?a:b)#define min(a,b) (a<b?a:b)int main(){    int T;    int n,m;    scanf("%d",&T);    while(T--)    {        scanf("%d%d",&n,&m);        if(n<m)        {            int temp=n;            n=m;m=temp;        }        if(m==1)        {            printf("%d\n",n/2);            continue;        }        printf("%d\n",n/2+m/2);    }    return 0;}