高精度乘法模

2019-04-13 12:20发布

站内文章 / 模拟电子
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#include #include #include using namespace std; int multiplicative(int a[], int len1, int b[], int len2, int c[]) { int ans; for(int i = 1; i <= len1; i++) { ans = 0; for(int j = 1; j <= len2; j++) { c[i+j-1] = c[i+j-1]+ans+a[i]*b[j]; // i, j必须要从1开始，不然i+j-1会等于-1,出错； ans = (c[i+j-1])/10; c[i+j-1] %= 10; } c[len2+i] = ans; } return len1+len2; } int main() { char a[505], b[505]; int c[505], d[505], e[1010]; scanf("%s%s", a, b); memset(c, 0, sizeof(c)); memset(d, 0, sizeof(d)); memset(e, 0, sizeof(e)); int len1 = strlen(a), len2 = strlen(b), len3; for(int i = 1; i <= len1; i++) c[i] = a[len1-i] - '0';//从1开始 for(int i = 1; i <= len2; i++) d[i] = b[len2-i] - '0'; len3 = multiplicative(c, len1, d, len2, e); int i; for(i = len3; i > 1; i--) if(e[i]) break; for(; i >= 1; i--) printf("%d", e[i]); printf(" "); }

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