Codeforces Beta Round #93 (Div. 2 Only) A题

这题，我弄了好久，就因为一个len=0.0未进行声明，导致我错了好几次！哎，无语了#include <iostream>#include <cstdio>#include <cstring>#include <cmath>using namespace std;int main(){    int n,k,i,j;    double x[205],y[205],len;    cin>>n>>k;    for(i=0; i<n; i++)    {        cin>>x[i]>>y[i];    }    len=0.0;    for(i=0; i<n-1; i++)    {        len+=sqrt((x[i]-x[i+1])*(x[i]-x[i+1])+(y[i]-y[i+1])*(y[i]-y[i+1]));    }    len*=k;    len/=50;    printf("%0.9llf\n",len);    return 0;}