poj 2756 Autumn is a Genius

poj 2756 Autumn is a Genius

#include <stdio.h>#include <string>#include <algorithm>using std::string;const int MAX_B = 5120;char buf[MAX_B];int id = 0, len = 0;inline char getFromBuf(){if (id >= len){len = fread(buf, 1, MAX_B, stdin);id = 0;}return buf[id++];}void getIntFromBuf(string &n){char a = getFromBuf();while ((a == ' ' || a == 'n') && len) a = getFromBuf();bool sign = true;if (a == '-' || a == '+'){if (a == '-') sign = false;a = getFromBuf();}n.clear();while ((a != ' ' && a != 'n') && len){n.push_back(a);a = getFromBuf();}if (sign) n.push_back('+');else n.push_back('-');}string operator+(string &a, string &b){string c;int N1 = (int)a.size(), N2 = (int)b.size();int carry = 0;for (int i = N1-1, j = N2-1; i>=0 || j>=0 || carry; i--, j--){int an = i>=0? a[i]-'0' : 0;int bn = j>=0? b[j]-'0' : 0;int sum = an + bn + carry;carry = sum / 10;c.push_back(sum % 10 + '0');}reverse(c.begin(), c.end());return c;}string operator-(string &a, string &b){string c;int N1 = (int)a.size(), N2 = (int)b.size();int carry = 0;for (int i = N1-1, j = N2-1; i>=0 || j>=0 || carry; i--, j--){int an = i>=0? a[i]-'0' : 0;int bn = j>=0? b[j]-'0' : 0;int sum = an - bn + carry;if (sum < 0){carry = -1;sum += 10;}else carry = 0;c.push_back(sum % 10 + '0');}reverse(c.begin(), c.end());return c;}int cmpAbsStr(string &a, string &b){if (a.size() < b.size()) return -1;else if (a.size() > b.size()) return 1;if (a == b) return 0;for (int i = 0; i < (int)a.size(); i++){if (a[i] < b[i]) return -1;else if (a[i] > b[i]) return 1;}return 0;}int main(){int T;scanf("%d", &T);getchar();string n1, n2;while (T--){getIntFromBuf(n1);getIntFromBuf(n2);if (n1[n1.size()-1] == '+' && n2[n2.size()-1] == '+'|| n1[n1.size()-1] == '-' && n2[n2.size()-1] == '-'){if (n1[n1.size()-1] == '-' && n2[n2.size()-1] == '-') putchar('-');n1.erase(n1.size()-1); n2.erase(n2.size()-1);string c = n1 + n2;puts(c.c_str());}else{if (n1[n1.size()-1] == '-' && n2[n2.size()-1] == '+') n1.swap(n2);n1.erase(n1.size()-1), n2.erase(n2.size()-1);int sign = cmpAbsStr(n1, n2);if (sign == 0) puts("0");else if (sign == 1){string c = n1 - n2;puts(c.c_str());}else{string c = n2 - n1;putchar('-');puts(c.c_str());}}}return 0;}