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高精度
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/* | |
高精度加减乘除类: | |
@param: 倒序的两个高精度数组 | |
@return: 字符串表示的结果 | |
*/ | |
/* --------- 高精度加法 ----------- */ | |
string bigadd(vector<int>& a, vector<int>& b) { | |
if (a.size() < b.size()) return bigadd(b, a); | |
int t = 0; | |
string ans = ""; | |
for (int i = 0; i < a.size(); ++i) { | |
t += a[i]; | |
if (i < b.size()) t += b[i]; | |
ans += to_string(t % 10); | |
t /= 10; | |
} | |
if (t) ans += to_string(t); | |
reverse(ans.begin(), ans.end()); | |
return ans; | |
} | |
/* --------- 高精度减法 ----------- */ | |
// a < b return -1; | |
int comp(vector<int>& a, vector<int>& b) { | |
if (a.size() < b.size()) return -1; | |
else if (a.size() > b.size()) return 1; | |
else { | |
int i = a.size() - 1; | |
while (i && a[i] == b[i]) --i; | |
if (a[i] < b[i]) return -1; | |
return 1; | |
} | |
} | |
string bigsub (vector<int>& a, vector<int>& b) { | |
if (comp(a, b) < 0) return "-" + bigsub(b, a); | |
string ans = ""; | |
for (int i = 0, t = 0; i < a.size(); ++i) { | |
t = a[i] - t; | |
if (i < b.size()) t -= b[i]; | |
ans += to_string((t + 10) % 10); | |
if (t < 0) t = 1; | |
else t = 0; | |
} | |
while (ans.size() > 1 && ans.back() == '0') ans.pop_back(); | |
reverse(ans.begin(), ans.end()); | |
return ans; | |
} | |
/* --------- 高精度乘法 ----------- */ | |
string bigmul (vector<int>& a, vector<int>& b) { | |
vector<int> c(a.size() + b.size(), 0); | |
for (int i = 0; i < a.size(); ++i) { | |
for (int j = 0; j < b.size(); ++j) { | |
c[i + j] += a[i] * b[j]; | |
} | |
} | |
for (int i = 0, t = 0; i < c.size(); ++i) { | |
t += c[i]; | |
c[i] = t % 10; | |
t /= 10; | |
} | |
while (c.size() > 1 && c.back() == 0) c.pop_back(); | |
string ans; | |
for (int i = c.size() - 1; i >= 0; --i) ans += c[i] + '0'; | |
return ans; | |
} | |
/* --------- 高精度除法 ----------- */ | |
/* | |
@params: a为正序被除数, b为除数, r是余数 | |
*/ | |
string bigdiv(vector<int>& a, int b, int& r) { | |
vector<int> c; | |
r = 0; | |
for (int i = 0; i < a.size(); ++i) { | |
r = r * 10 + a[i]; | |
c.push_back(r / b); | |
r %= b; | |
} | |
int ptr = 0; | |
while (ptr < c.size() - 1 && c[ptr] == 0) ++ptr; | |
string ans; | |
for (int i = ptr; i < c.size(); ++i) ans += c[i] + '0'; | |
return ans; | |
} | |
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