CodeForces-50A-Domino piling

A. Domino piling

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

You are given a rectangular board of M × N squares. Also you are given an unlimited number of standard domino pieces of 2 × 1 squares. You are allowed to rotate the pieces. You are asked to place as many dominoes as possible on the board so as to meet the following conditions:

1. Each domino completely covers two squares.

2. No two dominoes overlap.

3. Each domino lies entirely inside the board. It is allowed to touch the edges of the board.

Find the maximum number of dominoes, which can be placed under these restrictions.

Input

In a single line you are given two integers M and N — board sizes in squares (1 ≤ M ≤ N ≤ 16).

Output

Output one number — the maximal number of dominoes, which can be placed.

Sample test(s)

input

2 4

output

4

input

3 3

output

4

import java.util.*;public class DominoPiling {public static void main(String[] args) {Scanner inScanner = new Scanner(System.in);int m = 0, n = 0;int count = 0;m = inScanner.nextInt();n = inScanner.nextInt();if (m * n < 2)count=0;else if (n == 1) {count += (m / 2);// downward} else {int npart = n / 2;count += (npart * m);if(n%2==1){count+=(m/2);// downward}}System.out.println(count);}}

最先写完发现过于麻烦，后经过改进后重写

import java.util.*;public class DominoPilingPro {public static void main(String[] args) {Scanner inScanner = new Scanner(System.in);int m=inScanner.nextInt();int n=inScanner.nextInt();if(n%2==0){System.out.println(m*n/2);}else {System.out.println(m*n/2+m/2);}}}

多余的过程在于对边长的判断。其实，在运用“/”进行除法运算的过程中，整数相除采用了向下取证的方法，因此当边长不及多米诺牌长时，会出现除数比被除数大的情况，因而结果会取0，不需要在开头进行繁杂判断。