BestCoder Round #29 1001 GTY's math problem

GTY's math problem

Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 0    Accepted Submission(s): 0

Problem Description

   
   
   
   

    
    
    
    GTY is a GodBull who will get an Au in NOI . To have more time to learn algorithm knowledge, he never does his math homework. His math teacher is very unhappy for that, but she can't do anything because GTY can always get a good mark in math exams. One day, the math teacher asked GTY to answer a question. There are four numbers on the blackboard - 
    
    
    
    
    
    
    
     a,b,c,d . The math teacher wants GTY to compare 
    
    
    
    
    
    
    
     ab  with 
    
    
    
    
    
    
    
     cd . Because GTY never does his homework, he can't figure out this problem! If GTY can't answer this question correctly, he will have to do his homework. So help him!
   
   
   
   

 

Input

   
   
   
   

    
    
    
    Multi test cases (about 5000). Every case contains four integers a,b,c,d(
    
    
    
    
    
    
    
     1≤a,b,c,d≤1000 )separated by spaces. Please process to the end of file.
   
   
   
   

 

Output

   
   
   
   

    
    
    
    For each case , if 
    
    
    
    
    
    
    
     ab>cd  , print '>'. if 
    
    
    
    
    
    
    
     ab<cd  , print '<'. if 
    
    
    
    
    
    
    
     ab=cd  , print '='.
   
   
   
   

 

Sample Input

   
   
   
   

    
    
    
    2 1 1 2
2 4 4 2
10 10 9 11
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    >
=
<

题解思路：注意精度控制：
代码：

    
    
    
    
#include <set>
#include <map>
#include <cmath>
#include <time.h>
#include <queue>
#include <deque>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <algorithm>
using namespace std;
#define Max(a,b) a>b?a:b
#define Min(a,b) a>b?b:a
#define mem(a,b) memset(a,b,sizeof(a))
int dir[4][2]= {{1,0},{-1,0},{0,1},{0,-1}};
int main()
{
    int a,b,c,d;
    double ans1,ans2;
    while(scanf("%d %d %d %d",&a,&b,&c,&d) != -1)
    {
        ans1 = 1.0 * b * log10(a);
        ans2= 1.0 * d * log10(c);
        if(fabs(ans1 - ans2) < 1e-10)
            printf("=\n");
        else if(ans1 - ans2 > 1e-10)
            printf(">\n");
        else
            printf("<\n");
    }
    return 0;
}