#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
using namespace std;
char ans[10000];
int d = 10000;
int n;
int main() {
	cin >> n;
	memset(ans, -1, 10000);
	ans[0] = 2;
	for (int i = 1; i < n; i++) {

		for (int j = 0; ans[j] != -1; j++) {
			ans[j] *= 2;
		}
		for (int j = 0; ans[j] != -1; j++) {

			if (ans[j] > 9) {
				if (ans[j + 1] == -1) {
					ans[j + 1] = 0;
				}
				ans[j + 1] += ans[j] / 10;
				ans[j] %= 10;
			}

		}
	}
	int sum = 0;
	for (int i = 0; ans[i] != -1; i++) {
		sum++;
	}
	for (int i = sum - 1; i >= 0; i--) {
		cout << (char)(ans[i] + '0');
	}

	return 0;
}

#include <queue> #include <math.h> #include <stack> #include <stdio.h> #include <iostream> #include <vector> #include <iomanip> #include <string.h> #include <algorithm> using namespace std; #define LL long long const int N = 1e6 + 10; const int INF = 0x3f3f3f3f; int a[N],len,x; int main() { cin >> n; a[++len]=1; while(n--) { for(int i = 1; i <= len;i++) { a[i] = a[i]*2+x; x = a[i]/10; a[i] %= 10; } if(x) a[++len]=x; x = 0; } for(int i = len;i >= 1;i--) { cout <<a[i]; }

return 0;

}

#include<iostream>
#include<cstdio>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<string>
#include<stack>
#include<queue>
#define LL long long
const int N=1e3+10;
const int INT=0x3f3f3f3f;
using namespace std;
int a[N],n,len,x;
int main(){
	cin>>n;
	a[++len]=1;
	while(n--){
		for(int i=1;i<=len;i++){
			a[i]=a[i]*2+x;
			x=a[i]/10;
			a[i]%=10;
		}
		if(x){
			a[++len]=x;
		}
		x=0;
	}
	for(int i=len;i>=1;i--){
		cout<<a[i];
	}
	return 0;
}

#include <iostream> #include <string> #include <cstring> #include <algorithm> using namespace std; char ans[10000]; int d = 10000; int n; int main() { cin >> n; memset(ans, -1, 10000); ans[0] = 2; for (int i = 1; i < n; i++) {

for (int j = 0; ans[j] != -1; j++) {
		ans[j] *= 2;
	}
	for (int j = 0; ans[j] != -1; j++) {

		if (ans[j] > 9) {
			if (ans[j + 1] == -1) {
				ans[j + 1] = 0;
			}
			ans[j + 1] += ans[j] / 10;
			ans[j] %= 10;
		}

	}
}
int sum = 0;
for (int i = 0; ans[i] != -1; i++) {
	sum++;
}
for (int i = sum - 1; i >= 0; i--) {
	cout << (char)(ans[i] + '0');
}

return 0;

}

#include <iomanip>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
using namespace std;
const int N=1e5+10;
const int INF=0x3f3f3f3f;
string a,b;
int lena,lenb,lenc,a1[N],b1[N],c1[N],x;
int main(){
	cin>>a>>b;
	lena=a.size();
	lenb=a.size();
	for(int i=0;i<lena;i++){
		a1[i]=a[lena-i-1]-'0';
	}
	for(int i=0;i<lenb;i++){
		b1[i]=b[lenb-i-1]-'0';
	}
	for(int i=0;i<lenb;i++){
		x=0;
		for(int j=0;j<lena;j++){
			c1[i+j]+=a1[j]*b1[i]+x;
			x=c1[i+j]/10;
			c1[i+j]%=10;
		}
		c1[lena+i]=x;
	}
	lenc=lena+lenb;
	while(c1[lenc]==0&&lenc>0){
		lenc--;
	}
	for(int i=lenc;i>=0;i--){
		cout<<c1[i];
	}
return 0;
}

#include<bits/stdc++.h>
using namespace std;
#define LL long long
int n,a[105],len;
int x;
int main(){
    cin>>n;
    a[++len]=1;
    while(n--){
    	for(int i=1;i<=len;i++){
    		a[i]=a[i]*2+x;
    		x=a[i]/10;
    		a[i]%=10;
    	} 
    	if(x){
    		a[++len]=x;
    	}
    	x=0;
    }
    for(int i=len;i>=1;i--){
    	cout<<a[i];
    }
}

这道题只要用高精度算法就可以AC

但是要注意删除前导零和进位，而且数组的第一项要设置为1

#include<bits/stdc++.h>
using namespace std;
int a[100000];
int len=2,x;
int r,y;
int main(){
	cin>>r;a[1]=1;
	while(r--){
		for(int i=1;i<=len;i++){
			a[i]=a[i]*2+x;
			x=a[i]/10;
			a[i]%=10;
		}
		if(x!=0)a[++len]=x;
		x=0;
	}while(a[len]==0){
		len--;
	}
	for(int i=len;i>=1;i--)cout<<a[i];
	return 0;
}

#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<string>
#include<cstring>
const int INF=0x3f3f3f3f;
const int N=1e5+10;
using namespace std;
int a[N],n,len,x;
int main(){
	cin>>n;
	a[++len]=1;
	while(n--)
	{
		for(int i =1;i<=len;i++ )
		{
			a[i]=a[i]*2+x;
			x=a[i]/10;
			a[i]%=10;
		}
		if(x)
		a[++len]=x;
		x=0;
	}
	for(int i=len;i>=1;i--)
	{
		cout<<a[i];
	}
	return 0;
}

#include <stdio.h>
#include <string.h>
int main()
{
       int n;
       scanf("%d",&n);
       int a[35];
       memset(a,0,sizeof(a));
       a[1]=1;
       int i,j,len=1;
       for(i=1;i<=n;i++)
       {
           int cf=0;
              for (j=1;j<=len;j++)
               {
                      a[j]=a[j]*2+cf;
                      cf=a[j]/10;

                      a[j]=a[j]%10;
               }
               while (cf!=0)
               {
                      a[++len]=cf%10;
                      cf/=10;
               }
        }
     for (i=len;i>=1;i--)
                 printf("%d",a[i]);
     printf("\n");
     return 0;
}