9892. C0n + … + Cnn
Given a non-negative integer n, find the sum of binomial coefficients:
Input. One non-negative integer n (n ≤ 60).
Output. Print the value of the sum.
|
Sample
input |
Sample
output |
|
2 |
4 |
SOLUTION
combinatorics
Algorithm analysis
The formula of
the binomial theorem is as follows:
If we set a = b = 1, then this
relation takes the following form:
or
Thus, the
indicated sum equals 2n.
Example
If n = 1, then 
= 1 + 1 = 2;
If n = 2, then 
= 1 + 2 + 1 = 4;
If n = 3, then 
= 1 + 3 + 3 + 1 = 8;
Algorithm realization
Read the
input value of n.
scanf("%lld",
&n);
Compute and
print the result, the value of 2n.
res = 1LL << n;
printf("%lld\n",
res);
Python realization
Read the
input value of n.
n = int(input())
Compute and
print the result, the value of 2n.
res = 1 << n
print(res)