从一个数组中查找和目标数最近的或者相等的数
大疆无人机笔试题，二分法求解：
1 #include <iostream> 2 #include <stdlib.h> 3 #include <math.h> 4 #include <stdio.h> 5 using namespace std; 6 int binarySearchKey(int *arr,int goal,int len) 7 { 8 int i; 9 for(i = 0;i < len;++i) 10 { 11 cout<<arr[i]<<" "; 12 } 13 int targetindex = 0; 14 int left = 0,right = 0; 15 for(right = len - 1; left != right;) 16 { 17 int midIndex = (right + left)/2; 18 int mid = (right - left); 19 int midValue = arr[midIndex]; 20 if(goal == midValue) 21 { 22 return midIndex; 23 } 24 if(goal > midValue) 25 { 26 left = midIndex; 27 } 28 else 29 { 30 right = midIndex; 31 } 32 if(mid <= 1) 33 { 34 break; 35 } 36 } 37 int rightnum = arr[right]; 38 int leftnum = arr[left]; 39 int ret = abs((rightnum - leftnum)/2) > abs(rightnum -goal) ? rightnum : leftnum; 40 return ret; 41 } 42 int main() 43 { 44 int a[8] = {0,1,2,3,5,6,8,9}; 45 int k = binarySearchKey(a,4,8); 46 cout<<"k = " << k <<endl; 47 }
