CSP-S / J Bioinformatics 1170: calculated N-th power of 2 - through an informatics (c ++)

CSP-SJ Bioinformatics Download
time limit: 1000 ms memory limit: 65536 KB
4943: submitted Number: Number 9709 by
[Title] Description
values for any given a positive integer N (N≤100), calculates the n-th power of 2 .

[INPUT]
enter a positive integer N.

[Output]
output value of the N-th power of 2.

[Input] Sample
5
[output] Sample
32
[Source]

No

代码如下：
#include<iostream>
#include<cstring>
#define N 50
using namespace std;
int a[N],n,lena=1;
int main(){
    cin>>n;
    a[0]=1;
    while(n--){
        for(int i=0;i<lena;i++)a[i]*=2;
        for(int i=0;i<lena;i++){
            if(a[i]>9){
                a[i+1]++;
                a[i]-=10;
                if(i==lena-1)lena++;
            }
        }
    }
    for(int i=lena-1;i>=0;i--)cout<<a[i];
    cout<<endl;
}