易水人去,明月如霜。
Description
Consider the natural numbers from 1 to N. By associating to each number a sign (+ or -) and calculating the value of this expression we obtain a sum S. The problem is to determine for a given sum S the minimum number N for which we can obtain S by associating signs for all numbers between 1 to N. For a given S, find out the minimum value N in order to obtain S according to the conditions of the problem.Input
The only line contains in the first line a positive integer S (0< S <= 100000) which represents the sum to be obtained.Output
The output will contain the minimum number N for which the sum S can be obtained.Sample Input
12Sample Output
7Hint
The sum 12 can be obtained from at least 7 terms in the following way: 12 = -1+2+3+4+5+6-7. 太简单 #include <cstdio> #include <cstring> #include <cmath> using namespace std; int main() { int n; scanf("%d",&n); for(int i=1;i<=n;i++) { if((i*(i+1))/2<n) continue; int d=i*(i+1)/2; if((d-n)%2==0) { printf("%d",i); break; } } return 0; }