PAT甲级A1065 A+B and C (64bit) （20 分）

Given three integers A, B and C in [−2​63​​,2​63​​], 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

题意：给出三个64位的数字，让你判断 a+b与c的大小关系

思路：使用long long 类型存储数字。a+b的结果一定要存储在一个long long类型的变量中，不能直接用a+b与c比较大小。

注意边界，若a>0,b>0且a+b<=0则说明越界了，反之也是。

参考代码：

#include<cstdio>
using namespace std;
int main()
{
	int n;
	long long a,b,c,d;
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%lld %lld %lld",&a,&b,&c);
		d=a+b;
		if(a>0&&b>0&&d<=0)
			printf("Case #%d: true\n",i);
		else if (a<0&&b<0&&d>=0)
			printf("Case #%d: false\n",i);
		else if(d>c) 
			printf("Case #%d: true\n",i);
		else 
			printf("Case #%d: false\n",i);
	}
	return 0;
}