数字存储采用vector
例如123456789存储为987654321
低位在前高位在后
vector<int> mul(const vector<int> &A, const vector<int> &B) {
vector<int> C(A.size() + B.size());
for (int i = 0; i < A.size(); i++) {
for (int j = 0; j < B.size(); j++) {
C[i + j] += A[i] * B[j];
}
}
int t = 0;
for (int i = 0; i < C.size(); i++) {
t += C[i];
C[i] = t % 10;
t /= 10;
}
while (C.size() > 1 && C.back() == 0) C.pop_back();
return C;
}
解释先欠着,有时间了再补吧