ACM--贪心--数学--A-B Game--水

 OJ地址：http://acm.fzu.edu.cn/problem.php?pid=2147

                                               Problem 2147 A-B Game

Accept: 1158    Submit: 2769
Time Limit: 1000 mSec    Memory Limit : 32768 KB

 Problem Description

Fat brother and Maze are playing a kind of special (hentai) game by two integers A and B. First Fat brother write an integer A on a white paper and then Maze start to change this integer. Every time Maze can select an integer x between 1 and A-1 then change A into A-(A%x). The game ends when this integer is less than or equals to B. Here is the problem, at least how many times Maze needs to perform to end this special (hentai) game.

 Input

The first line of the date is an integer T, which is the number of the text cases.

Then T cases follow, each case contains two integers A and B described above.

1 <= T <=100, 2 <= B < A < 100861008610086

 Output

For each case, output the case number first, and then output an integer describes the number of times Maze needs to perform. See the sample input and output for more details.

 Sample Input

25 310086 110

 Sample Output

Case 1: 1Case 2: 7

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题意：给出两个数A,B（A>B），每次操作A-(A%x),x任选，问至少需要几次操作能够使得A

解法：简单贪心。每次x都取A/2+1。

代码:

 #include
 #include
 #include
 using namespace std;
 /**
    输入A、B（B>A;
      cin>>B;
      index++;
      while(A>B){
         A=A-(A%(A/2+1));
         result++;
      }
      printf("Case %d: ",index);
      cout<