必须感叹下,大数模板就是好用!
AC代码:
#include <cstdio> #include <cmath> #include <algorithm> #include <cstring> #include <utility> #include <string> #include <iostream> #include <map> #include <set> #include <vector> #include <queue> #include <stack> using namespace std; #define eps 1e-10 #define inf 0x3f3f3f3f #define PI pair<int, int> typedef long long LL; const int maxn = 1e4 + 5; struct BigInteger { vector<int>s; //12345--54321 void DealZero() { //处理前导0 for(int i = s.size() - 1; i > 0; --i){ if(s[i] == 0) s.pop_back(); else break; } } BigInteger operator = (long long num) { // 赋值运算符 s.clear(); vector<int>tmp; do{ s.push_back(num % 10); num /= 10; }while(num); return *this; } BigInteger operator = (const string& str) { // 赋值运算符 s.clear(); for(int i = str.size() - 1; i >= 0; --i) s.push_back(str[i] - '0'); this->DealZero(); return *this; } BigInteger operator + (const BigInteger& b) const { BigInteger c; c.s.clear(); int len1 = s.size(), len2 = b.s.size(); for(int i = 0, g = 0; g > 0 || i < len1 || i < len2; ++i) { int x = g; if(i < len1) x += s[i]; if(i < len2) x += b.s[i]; c.s.push_back(x % 10); g = x / 10; } return c; } //大数减小数 BigInteger operator - (const BigInteger& b) const { BigInteger c; c.s.clear(); int len1 = s.size(), len2 = b.s.size(); for(int i = 0, g = 0; i < len1 || i < len2; ++i) { int x = g; if(i < len1) x += s[i]; g = 0; if(i < len2) x -= b.s[i]; if(x < 0) { g = -1; //借位 x += 10; } c.s.push_back(x); } c.DealZero(); return c; } BigInteger operator * (const BigInteger& b) const { BigInteger c, tmp; c.s.clear(); int len1 = s.size(), len2 = b.s.size(); for(int i = 0; i < len1; ++i) { tmp.s.clear();tmp; int num = i; while(num--) tmp.s.push_back(0); int g = 0; for(int j = 0; j < len2; ++j) { int x = s[i] * b.s[j] + g; tmp.s.push_back(x % 10); g = x / 10; } if(g > 0) tmp.s.push_back(g); c = c + tmp; } c.DealZero(); return c; } //单精度除法 BigInteger operator / (const int b) const { BigInteger c, tmp; c.s.clear(); int len = s.size(); int div = 0; for(int i = len - 1; i >= 0; --i) { div = div * 10 + s[i]; while(div < b && i > 0) { div = div * 10 + s[--i]; } tmp.s.push_back(div / b); div %= b; } for(int i = tmp.s.size() - 1; i >= 0; --i) c.s.push_back(tmp.s[i]); c.DealZero(); return c; } bool operator < (const BigInteger& b) const { int len1 = s.size(), len2 = b.s.size(); if(len1 != len2) return len1 < len2; for(int i = len1 - 1; i >= 0; --i) { if(s[i] != b.s[i]) return s[i] < b.s[i]; } return false; //相等 } bool operator <= (const BigInteger& b) const { return !(b < *this); } string ToStr() { string ans; ans.clear(); for(int i = s.size()-1; i >= 0; --i) ans.push_back(s[i] + '0'); return ans; } //大数开方 /**大数开方用法说明: 字符串必须从第二个位置开始输入,且s[0] = '0' scanf("%s", s+1); */ BigInteger SQRT(char *s) { string p = ""; s[0]='0'; if(strlen(s)%2 == 1) work(p, 2, s+1, 0); else work(p, 2, s, 0); BigInteger c; c.s.clear(); c = p; return c; } //开方准备 //------------------------------------ int l; int work(string &p, int o,char *O,int I){ char c, *D=O ; if(o>0) { for(l=0;D[l];D[l++]-=10) { D[l++]-=120; D[l]-=110; while(!work(p, 0, O, l)) D[l]+=20; p += (char)((D[l]+1032)/20); } } else { c=o+(D[I]+82)%10-(I>l/2)*(D[I-l+I]+72)/10-9; D[I]+=I<0 ? 0 : !(o=work(p, c/10,O,I-1))*((c+999)%10-(D[I]+92)%10); } return o; } //----------------------------------------- }; ostream& operator << (ostream &out, const BigInteger& x) { for(int i = x.s.size() - 1; i >= 0; --i) out << x.s[i]; return out; } istream& operator >> (istream &in, BigInteger& x) { string s; if(!(in >> s)) return in; x = s; return in; } int main() { BigInteger a, b; while(cin >> a >> b) { cout << a * b << "\n"; } return 0; }
如有不当之处欢迎指出!