There are two sisters Alice and Betty. You have n n n candies. You want to distribute these n n n candies between two sisters in such a way that:
Your task is to calculate the number of ways to distribute exactly n n n candies between sisters in a way described above. Candies are indistinguishable.
Formally, find the number of ways to represent n n n as the sum of n=a+b n=a+b n=a+b , where a a a and b b b are positive integers and a>b a>b a>b .
You have to answer t t t independent test cases.
The first line of the input contains one integer t t t ( 1≤t≤104 1 \le t \le 10^4 1≤t≤104 ) — the number of test cases. Then t t t test cases follow.
The only line of a test case contains one integer n n n ( 1≤n≤2⋅109 1 \le n \le 2 \cdot 10^9 1≤n≤2⋅109 ) — the number of candies you have.
For each test case, print the answer — the number of ways to distribute exactly n n n candies between two sisters in a way described in the problem statement. If there is no way to satisfy all the conditions, print 0 0 0 .
6 7 1 2 3 2000000000 763243547
3 0 0 1 999999999 381621773
输出(n-1)/2即可。
#include <bits/stdc++.h> using namespace std; int main() { int t; cin>>t; while(t--) { long long n; scanf("%lld",&n); cout<<(n-1)/2; } return 0; }
Codeforces Round #634 A. Candies and Two Sisters（水）
原文：https://www.cnblogs.com/lipoicyclic/p/12695570.html