3537 - 函数计算
f(n)=-1+2-3+..+((-1)^n)*n
你的任务是给定n，计算f(n)的值
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Input
每组数据第一行为一个正整数n(n在int范围内）
Output
输出f(n)的值
Examples
Input
1 2 7
Output
-1 1 -4
Solution C++
#include <iostream> #include <vector> #include <algorithm> #include <string> #include <sstream> #include <cstring> #include <cstdio> #include <cstdlib> #include <cmath> #include <queue> #include <stack> #include <map> #include <set> #include <numeric> #include <cassert> #include <complex> #include <ctime> #define clr(x,a) memset(x,a,sizeof(x)) #define sz(x) (int)x.size() #define rep(i,n) for(int i=0;i<n;i++) #define repeat(i, a, b) for(int i=(a);i<=(b);i++) #define all(v) (v).begin(), (v).end() #define Unique(store) store.resize(unique(store.begin(),store.end())-store.begin()) #define X first #define Y second using namespace std; const int N=123456+10; int main () { //freopen("in.txt","r",stdin); //freopen("out.txt","w",stdout); int n; while (cin>>n) { int ret; if (n%2==0) { ret=n/2; } else { ret=n/2-n; } cout<<ret<<endl; } return 0; }