【笔试记录】2020.7.25 百度二面 （手撕开方：二分法）

手撕开方sqrt()，要求不能使用自带的math库等

#include 
#include 
#include 
#include 
#include 
#include 
#include "limits.h"

using namespace std;

float abss( float a, float b){
    if( a < b)
        return b-a;
    else
        return a-b;
}
//开方：math不能用
float sqrt(float m, float err){
    float low = 0, high = m;
    float anws = (low+high)/2;
        
    while( abss(m, anws*anws) > err ){
        if( anws*anws < m ){
            low = anws;
        }else{
            high = anws;
        }
        anws = (low+high)/2;
    }
    return anws;
}

int main(int argc, const char * argv[]) {
    cout << sqrt(2.0, 0.1) << endl;
    cout << sqrt(2.0, 0.001) << endl;
    cout << sqrt(4.0, 0.001) << endl;
    cout << sqrt(-4.0, 0.001) << endl;
    
    return 0;
}