GDUFE ACM-1006
题目:http://acm.gdufe.edu.cn/Problem/read/id/1006
Hailstone HOTPO
Time Limit: 2000/1000ms (Java/Others)
Problem Description:
The hailstone sequence is formed in the following way: (1) If n is even, divide it by 2 to get n' (2) If n is odd, multiply it by 3 and add 1 to get n' It is conjectured that for any positive integer number n, the sequence will always end in the repeating cycle: 4, 2, 1, 4, 2, 1,... Suffice to say , when n == 1, we will say the sequence has ended. Write a program to determine the largest value in the sequence for a given n.
Input:
The first line of input contains a single integer P, (1<= P <= 100000), which is the number of data set s that follow. Each data set should be processed identically and independently. Each data set consists of a single line of input consisting of two space separated decimal integers. The first integer is the data set number. The second integer is n, (1 <= n <= 100,000), which is the starting value.
Output:
For each data set there is a single line of output consisting of the data set number, a single space, and the largest value in the sequence starting at and including n.
Sample Input:
4 1 1 2 3 3 9999 4 100000
Sample Output:
1 1 2 16 3 101248 4 100000
思路:判断是基数还是偶数,然后按题目要求执行,判断执行后的数与执行前的数哪个比较大,把大的留下来,直到得出1,结束
难度:简单
代码:
1 #include<stdio.h> 2 int main() 3 { 4 int n,a,b,c; 5 while(scanf("%d",&n)!=EOF) 6 { 7 while(n--) 8 { 9 scanf("%d %d",&a,&b); 10 c=0; 11 if(b==1) c=1; 12 while(b!=1) 13 { 14 if(b>c) 15 c=b; 16 if(b%2==0) 17 b=b/2; 18 else b=b*3+1; 19 } 20 printf("%d %d\n",a,c); 21 } 22 } 23 return 0; 24 }