1065 A+B and C (64bit) （20 point(s)）

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

经验总结：

这一题，要注意，A+B是有可能溢出的，而我们恰恰可以利用溢出的特性来进行判断，比如A、B如果都大于0，A+B小于0，那么A+B一定大于C，因为C肯定没有溢出，其他的情况也是这个道理~

AC代码

#include <cstdio>

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