#include using namespace std; // change input here // p & q must be positive! string p = "8232378127318237"; string q = "23182371823712312"; // smaller between s1 and s2 bool sml(string s1, string s2) { int len = s1.size(); for (int i = 0; i < len; i++) { if (s1[i] < s2[i]) return true; else if (s1[i] > s2[i]) return false; } return false; } // addition string add(string s1, string s2) { int sz1 = s1.size(), sz2 = s2.size(); int len = max(sz1, sz2); while (sz1++ < len) { s1 = "0" + s1; } while (sz2++ < len) { s2 = "0" + s2; } int col = 0, cry = 0; string s = ""; for (int i = len - 1; i >= 0; i--) { int d1 = s1[i] - '0'; int d2 = s2[i] - '0'; col = d1 + d2 + cry; cry = col / 10; s = to_string(col % 10) + s; } if (cry) s = "1" + s; s.erase(0, s.find_first_not_of('0')); return s.empty() ? "0" : s; } // subtraction string sub(string s1, string s2) { int sz1 = s1.size(), sz2 = s2.size(); int len = max(sz1, sz2); while (sz1++ < len) { s1 = "0" + s1; } while (sz2++ < len) { s2 = "0" + s2; } int col = 0; string s = ""; bool swap = false; if (sml(s1, s2)) { swap = true; s1.swap(s2); } for (int i = len - 1; i >= 0; i--) { int d1 = s1[i] - '0'; int d2 = s2[i] - '0'; col = d1 - d2; if (col >= 0) { s = to_string(col) + s; } else { int j = i - 1; while (j >= 0) { int d3 = s1[j] - '0' - 1; if (d3 >= 0) { s1[j] = d3 + '0'; break; } else { s1[j] = '9'; j--; } } s = to_string(col + 10) + s; } } s.erase(0, s.find_first_not_of('0')); if (swap) { s = '-' + s; } return s.empty() ? "0" : s; } // multiplication string mul(string s1, string s2) { int sz1 = s1.size(), sz2 = s2.size(); int len = max(sz1, sz2); while (sz1++ < len) { s1 = "0" + s1; } while (sz2++ < len) { s2 = "0" + s2; } if (len == 1) { int d1 = s1[0] - '0'; int d2 = s2[0] - '0'; return to_string(d1 * d2); } int l = len / 2, r = len - len / 2; string s = ""; string s10 = s1.substr(0, l); string s11 = s1.substr(l, r); string s20 = s2.substr(0, l); string s21 = s2.substr(l, r); string p0 = mul(s10, s20); string p1 = mul(s11, s21); string p2 = mul(add(s10, s11), add(s20, s21)); string p3 = sub(p2, add(p0, p1)); for (int i = 0; i < 2 * r; i++) { p0 += "0"; } for (int i = 0; i < r; i++) { p3 += "0"; } s = add(add(p0, p1), p3); s.erase(0, s.find_first_not_of('0')); return s.empty() ? "0" : s; } int main() { cout << add(p, q) << "\n"; cout << sub(p, q) << "\n"; cout << mul(p, q) << "\n"; return 0; }

[Challenge] Long Long + - *