PAT1065 A+B and C (64bit) (20)

1065. A+B and C (64bit) (20)

时间限制

100 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

HOU, Qiming

Given three integers A, B and C in [-2⁶³, 2⁶³], you are supposed to tell whether A+B > C.

Input Specification:

The first line of the input gives the positive number of test cases, T (<=10). Then T test cases follow, each consists of a single line containing three integers A, B and C, separated by single spaces.

Output Specification:

For each test case, output in one line "Case #X: true" if A+B>C, or "Case #X: false" otherwise, where X is the case number (starting from 1).

Sample Input:

31 2 32 3 49223372036854775807 -9223372036854775808 0

Sample Output:

Case #1: falseCase #2: trueCase #3: false

题目：大整数加法+字符串比较大小

解法：按位操作

启示：string 取最后，边取边删除，尾部对齐

Code：

#include <iostream>#include <string>#include <stdio.h>std::string DelZero(std::string result) {  int start_pos = -1;  for (int i = 0; i < result.size(); i++) {    if (result[i] != '0') {      start_pos = i;      break;    }  }  if (start_pos == -1) {    return "0";  }  else {    result.erase(0, start_pos);    return result;  }}bool Compare(std::string a, std::string b) {  if (a[0] == '-' && b[0] == '-') {    a.erase(0, 1);    b.erase(0, 1);    return Compare(b, a);  }  else if (a[0] == '-' && b[0] != '-') {    return false;  }  else if (b[0] == '-' && a[0] != '-') {    return true;  }  else {    if (a.size() > b.size()) {      return true;    }    else if (a.size() < b.size()) {      return false;    }    else {      for (int i = a.size() - 1; i > 0; i--) {        if (a[i] - '0' < b[i] - '0') {          return false;        }        else if (a[i] - '0' > b[i] - '0') {          return true;        }      }      if (a[0] - '0' > b[0] - '0') {        return true;      }      else {        return false;      }    }  }}std::string Add(std::string a, std::string b) {  int size = a.size() > b.size() ? b.size() : a.size();  std::string long_str = a.size() > b.size() ? a : b;  std::string result = "";  int mark = 0;  int gap = a.size() > b.size() ? a.size() - size : b.size() - size;  for (int i = 0; i < size; i++) {    int num = (a.back() - '0') + (b.back() - '0') + mark;    if (num >= 10) {      mark = 1;      char r[10];      snprintf(r, sizeof(r), "%d", abs(num));      result.insert(0, r);    }    else {      mark = 0;      char r[10];      snprintf(r, sizeof(r), "%d", abs(num));      result.insert(0, r);    }    a.erase(a.size() - 1, 1);    b.erase(b.size() - 1, 1);    long_str.erase(long_str.size() - 1, 1);  }  for (int i = 0; i < gap; i++) {    int num = (long_str.back() - '0') + mark;    if (num >= 10) {      mark = 1;      char r[10];      snprintf(r, sizeof(r), "%d", abs(num));      result.insert(0, r);    }    else {      mark = 0;      char r[10];      snprintf(r, sizeof(r), "%d", abs(num));      result.insert(0, r);    }    long_str.erase(long_str.size() - 1, 1);  }  return result;}std::string Minus(std::string a, std::string b) {  std::string result = "";  std::string long_str = a.size() > b.size() ? a : b;  if (Compare(a, b)) {  // a > b    int mark = 0;    int size = a.size() > b.size() ? b.size() : a.size();    int gap = a.size() > b.size() ? a.size() - size : b.size() - size;    for (int i = 0; i < size; i++) {      int num = (a.back() - '0') - (b.back() - '0') - mark;      if (num < 0) {        mark = 1;        char r[10];        snprintf(r, sizeof(r), "%d", abs(num));        result.insert(0, r);      }      else {        mark = 0;        char r[10];        snprintf(r, sizeof(r), "%d", abs(num));        result.insert(0, r);      }      a.erase(a.size()-1, 1);      b.erase(b.size() - 1, 1);      long_str.erase(long_str.size() - 1, 1);    }    for (int i = 0; i < gap; i++) {      int num = (long_str.back() - '0') - mark;      if (num < 0) {        mark = 1;        char r[10];        snprintf(r, sizeof(r), "%d", abs(num));        result.insert(0, r);      }      else {        mark = 0;        char r[10];        snprintf(r, sizeof(r), "%d", abs(num));        result.insert(0, r);      }      long_str.erase(long_str.size() - 1, 1);    }    return result;  }  else {  // a <= b    if (a == b) return "0";    std::string result = Minus(b, a);    result.insert(0, "-");    return result;  }}std::string Handle(std::string a, std::string b) {  if (a[0] =='-' && b[0] == '-') {    a.erase(0, 1);    b.erase(0, 1);    std::string result = Add(a, b);        result = DelZero(result);    result.insert(0, "-");    return result;  }  else if (a[0] == '-' && b[0] != '-') {    a.erase(0, 1);    std::string result = Minus(b, a);    result = DelZero(result);    return result;  }  else if (b[0] == '-' && a[0] != '-') {    b.erase(0, 1);    std::string result = Minus(a, b);    result = DelZero(result);    return result;  }  else {    std::string result = Add(a, b);    // std::cout << result << "\n";    result = DelZero(result);    // std::cout << result << "\n";    return result;  }}int main() {  int n;  std::cin >> n;  for (int i = 0; i < n; i++) {    std::string a, b, c;    std::cin >> a;    std::cin >> b;    std::cin >> c;    std::string d = Handle(a, b);    // printf("%s\n", d.c_str());    if (Compare(d, c)) {      printf("Case #%d: true\n", i+1);    }    else {      printf("Case #%d: false\n", i+1);    }  }  system("pause");}