hdu 5879 小数极限(水)

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#include <iostream>#include <algorithm>#include <cstring>#include <cstdio>#include <queue>using namespace std;const int M=1e6+10;const double pi=3.14159; double dp[M+10];char str[M];int main(){dp[1]=1;for(int i=2;i<M;i++){double x=i;double y=1.0/(x*x);dp[i]=dp[i-1]+y;}while(scanf("%s",str)!=EOF){int flag=0;int i;int n=0;int len=strlen(str);for(i=0;i<len;i++){if(str[i]!='0'){break;}}int cur=i;if(len-cur>6)//因为保留5位小数 极限为1.64493 {printf("1.64493\n");continue;}else{for(int i=cur;i<min(len,cur+6);i++){n=n*10+str[i]-'0';}}printf("%.5lf\n",dp[n]);}return 0;}