Light oj 1214-Large Division (同余定理)

Posted 2020-06-29 Recoder

题目链接：http://lightoj.com/volume_showproblem.php?problem=1214

题意很好懂，同余定理的运用，要是A数被B数整除，那么A%B等于0。而A很大，那我就把A的每一位拆开，比如A是2341，那么2341=2000+300+40+1，然后你懂的...

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 using namespace std;
 5 char str[2005];
 6 int main()
 7 {
 8     int t;
 9     long long n;
10     cin >> t;
11     for(int ca = 1 ; ca <= t ; ca++) {
12         cin >> str >> n;
13         int len = strlen(str);
14         long long temp = 0 , begin = 0;
15         if(str[0] == ‘-‘)
16             begin++;
17         for(int i = begin ; i < len ; i++) {
18             temp = (temp * 10 % n + (str[i] - ‘0‘)) % n;
19         }
20         cout << "Case " << ca << ": ";
21         if(!temp)
22             cout << "divisible\n";
23         else
24             cout << "not divisible\n";
25     }
26 }