One algorithm question per day-simple-recursion-dropping of computing balls

This question is excerpted from <C LanguageExamples>

A ball falls freely from the height of 100 meters. After each landing, the ball jumps back to half of the original height and then falls. How much does it cost when he lands 10th times.

1. Known points: the distance that passes through when the first fall.

2. The last falling distance has a certain relationship with the next falling distance.

Package COM. jue. falldown; public class testfalldown {/*** @ Param ARGs */public static void main (string [] ARGs) {// todo auto-generated method stubsystem. out. println ("high:" + getdistance (10);} Private Static double getheight (INT index) {If (Index = 1) {return 100 ;} return getheight (index-1)/2;} static double getdistance (INT index) {If (Index = 1) {return getheight (1 );} else {return 2 * getheight (INDEX) + getdistance (index-1 );}}}