1.题目给出三个数a，b，c，要求判断a+b是否等于c。
2.使用string读取a和b，如果符号相同，按照字符串来处理，因为两个负数或者两个正数相加，会超过最大的取值范围。
3.如果符号不同，那么a+b一定会在范围内，可以使用long long进行处理和比。
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:
3 1 2 3 2 3 4 9223372036854775807 -9223372036854775808 0
Sample Output:
Case #1: false Case #2: true Case #3: false
AC代码：
[c language=”++”]
//#include<string>
//#include<stack>
//#include<unordered_set>
//#include <sstream>
//#include "func.h"
//#include <list>
#include <iomanip>
#include<unordered_map>
#include<set>
#include<queue>
#include<map>
#include<vector>
#include <algorithm>
#include<stdio.h>
#include<iostream>
#include<string>
#include<memory.h>
#include<limits.h>
#include<stack>
using namespace std;
/*
1000
9223372036854775807 -9223372036854775808 0
9223372036854775807 -9223372036854775806 0
9223372036854775808 -9223372036854775807 1
9223372036854775808 -9223372036854775807 2
1 1 0
1 1 2
1 1 3
-1 -1 0
-1 -1 -2
-1 -1 -3
*/
long long str2long(string a)
{
long long ans = 0;
for (int i = 0; i < a.size(); i++)
ans = ans * 10 + a[i] – ‘0’;
return ans;
}
string reverseStr(string a)
{
for (int i = 0; i < a.size() / 2; i++)
swap(a[i], a[a.size() – 1 – i]);
return a;
}
int main(void)
{
int n;
cin >> n;
for (int k = 0; k < n;k++)
{
bool isBigger = true;
string a, b;
cin >> a >> b;
bool aPositive = false;
bool bPositive = false;
//如果是负数，则进行标记和去掉负号
if (a[0] == ‘-‘)
{
a = a.substr(1);
aPositive = true;
}
if (b[0] == ‘-‘)
{
b = b.substr(1);
bPositive = true;
}
if ((aPositive&&bPositive) || (!aPositive&&!bPositive))
{
string ans = "";
if (a.size() > b.size()) swap(a, b);//保证a最短
a = reverseStr(a);
b = reverseStr(b);
int i = 0;
int carry = 0;
for (; i < a.size(); i++)
{
int sum = a[i] – ‘0’ + b[i] – ‘0’ + carry;
carry = sum / 10;
char c = sum % 10 + ‘0’;
ans = c + ans;
}
for (; i < b.size(); i++)
{
int sum = b[i] – ‘0’ + carry;
carry = sum / 10;
char c = sum % 10 + ‘0’;
ans = c + ans;
}
if (carry != 0)
{
char c = carry + ‘0’;
ans = c + ans;
}
//输入c
string c;
cin >> c;
bool cPositive = false;
if (c[0] == ‘-‘)
{
c = c.substr(1);
cPositive = true;
}
if (aPositive&&bPositive && cPositive)
{//a+b为负数，c为负数
if (ans.size() > c.size())//a+b的绝对值大于c的绝对值
isBigger = false;
else if (ans.size() == c.size())
{
for (int i = 0; i < ans.size(); i++)
{
if (ans[i]>c[i])
{//a+b的绝对值大于c的绝对值
isBigger = false;
break;
}
else if (ans[i] < c[i])
{//a+b的绝对值小于c的绝对值
isBigger = true;
break;
}
}
if (ans == c) isBigger = false;//相等的话，为false
}
else
isBigger = true;
}
else if (aPositive&&bPositive && !cPositive)
{//a+b为负数，c为正数
isBigger = false;
}
else if (!aPositive&&!bPositive && cPositive)
{//a+b为正数，c为负数
isBigger = true;
}
else
{//a+b为正数，c为正数
if (ans.size() > c.size())//a+b的绝对值大于c的绝对值
isBigger = true;
else if (ans.size() == c.size())
{
for (int i = 0; i < ans.size(); i++)
{
if (ans[i]>c[i])
{//a+b的绝对值大于c的绝对值
isBigger = true;
break;
}
else if (ans[i] < c[i])
{//a+b的绝对值小于c的绝对值
isBigger = false;
break;
}
}
if (ans == c) isBigger = false;//相等的话，为false
}
else
isBigger = false;
}
}
else
{
long long aInt = str2long(a), bInt = str2long(b);
long long ans;
if (!aPositive&&bPositive)
ans = aInt – bInt;
else
ans = bInt – aInt;
long long c;
cin >> c;
if (ans > c)
isBigger = true;
else isBigger = false;
}
if (isBigger)
printf("Case #%d: true\n", k + 1);
else
printf("Case #%d: false\n", k + 1);
}
return 0;
}
[/c]