#include<stdio.h> #include<stdlib.h> #include<string.h> #include<ctype.h> #include<math.h> int a[10005],s[10005]; //每次都计算 a数组*k void ans(int k){ //123 int i; //每一位都乘以k for(i=0;i<10000;i++){ a[i] = a[i]*k; } for(i=0;i<10000;i++){ a[i+1] = a[i+1] + a[i]/10; a[i] = a[i]%10; } } void add(){ int i; for(i=0;i<10000;i++){ s[i] = s[i]+a[i]; s[i+1] = s[i+1] + s[i]/10; s[i] = s[i]%10; } } int main(){ int n,i,j; scanf("%d",&n); for(i=1;i<=n;i++){ memset(a,0,sizeof(a)); a[0] = 1; for(j=1;j<=i;j++){ ans(2); } add(); } int p=1000; for(i=p;i>=0;i--){ if(s[i]!=0){ p = i; break; } } for(i=p;i>=0;i--){ printf("%d",s[i]); } return 0; } /************************************************************** Problem: 1281 User: admin Language: C Result: Accepted Time:60 ms Memory:1224 kb ****************************************************************/