java版的二分查找算法
package test;
public class Search ...{
public Search()...{
}
/** *//**
* @param data 从小到大排好序的数组
* @param goal 要查找的数
* @param left
* @param right
* @return 目标数的数组下标，没有找到为-1 ;
*/
public static int find(int[] data,int goal,int left,int right)...{
int mid = (left+right)/2 ;
if(left>right)...{
return -1 ;
}
if(goal==data[mid])...{
return mid ;
}
else if(goal<data[mid])...{
//注意right = mid -1 ;
return find(data,goal,left,mid-1);
}
else if(goal>data[mid])...{
return find(data,goal,mid+1,right);
}
return -1 ;
}
public static void main(String[] args)...{
int[] data = new int[]...{1,2,4,6,7};
int result =find(data,6,0,data.length-1) ;
System.out.println(result);
}
}
public class Search ...{ public Search()...{ } /** *//** * @param data 从小到大排好序的数组 * @param goal 要查找的数 * @param left * @param right * @return 目标数的数组下标，没有找到为-1 ; */ public static int find(int[] data,int goal,int left,int right)...{ int mid = (left+right)/2 ; if(left>right)...{ return -1 ; } if(goal==data[mid])...{ return mid ; } else if(goal<data[mid])...{ //注意right = mid -1 ; return find(data,goal,left,mid-1); } else if(goal>data[mid])...{ return find(data,goal,mid+1,right); } return -1 ; } public static void main(String[] args)...{ int[] data = new int[]...{1,2,4,6,7}; int result =find(data,6,0,data.length-1) ; System.out.println(result); } }