高精减模板

 1 int t;
 2 string a, b;
 3 int m[maxn;
 4 
 5 void BigInteger_subtract(string a, string b) {
 6     memset(m, 0, sizeof(m));
 7     int len = a.size();
 8     for(int i = len - 1; i >= 0; i--) {
 9         b += a[i];
10     }
11     if(b > a) {
12         string c = b;
13         b = a;
14         a = c;
15     }
16     t = 0;
17     for(int i = len - 1; i >= 0; i--) {
18         m[t] += a[i] - b[i];
19         if(m[t] < 0) {
20             m[t] += 10;
21             m[t + 1]--;
22         }
23         t++;
24     }
25     for(int i = t; i >= 0; i--) {
26         if(m[i] != 0) {
27             t = i + 1;
28             break;
29         }
30     }
31 }