A1065 A+Band C（64 bit）

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 (≤). 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

思路：

A+B相加之后可能会溢出，溢出的情况根据溢出后的数值分类讨论

问题：

部分测试点没通过

解决：

•A+B必须放在long long型变量中才可以与C比较，而不是在if的条件中直接比较,即 long long sum=A+B; if(sum>C)

•A B 最小值都是-2⁶³，相加得-2⁶⁴，故sum溢出后最小为0

#include <iostream>
using namespace std;
int main() {
    long long A, B, C;
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> A >> B >> C;
        long long sum = A + B;
        if (A < 0 && B < 0 && sum>=0)
            printf("Case #%d: false
", i+1);
        else if (A > 0 && B > 0 && sum< 0)
            printf("Case #%d: true
", i+1);
        else if (sum> C)
            printf("Case #%d: true
", i + 1);
        else
            printf("Case #%d: false
", i+1);    
    }
    return 0;
}