M29917: 牛顿迭代法

implementation, http://cs101.openjudge.cn/practice/29917/

#include<bits/stdc++.h>
using namespace std;
double const c=1e-6;
double a,x1,x2;
int cnt;
int main(){
    while(scanf("%lf",&a)!=EOF){
        cnt=0;
        x1=1;
        while(1){
            cnt++;
            x2=x1-(x1*x1-a)/(2*x1);
            if(abs(x1-x2)<=c)
                break;
            x1=x2;
        }
        printf("%d %.2lf\n",cnt,x2);
    }
    return 0;
}