【PAT】1065. A+B and C (64bit) (20)

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

---

分析：要考虑相加溢出的情况

(1)  a > 0 && b>0 && a+b <0  , 则 a+b > c

(2)  a < 0 && b<0 && a+b >0 , 则 a+b<c

此外，vc++6.0不支持long long型数据，而PAT上又不支持 __int64数据，所以最后选择用vs，采用long long 数据。

#include<iostream>
using namespace std;

int main()
{
	long long a,b,c,temp;
	int t,i;
	bool flag;
	scanf("%d",&t);
	for( i=1; i<=t; i++)
	{
		flag = true;
		scanf("%lld%lld%lld",&a,&b,&c);
		printf("Case #%d: ",i);
		temp = a+b;
		if(a>0 && b>0 && temp<=0){
			flag = true;
		}else if(a<0 && b<0 && temp>=0){
			flag = false;
		}else flag = temp > c;

		if(!flag)
			printf("false\n");
		else
			printf("true\n");
	}
	return 0;
}