解题思路

采用中分方法进行查找，考虑到是循环有序的数组，存在一边有序的情况，将中间值与最左边值比较，查看是否有序，则左有序，否则就是右有序。然后再确定待查找值的区域。

c++代码

//loopBuffer:循环有序数组 //length：循环有序数组长度 //value：待查找的数 //return:返回待查找数在数组中的位置 int BinarySearch(int* loopBuffer,int length, int value) { if(loopBuffer == NULL || length == 0) { cout<<"buffer is error"<<endl; return -1; } int left = 0; int right = length -1; int mid = (left+right)/2; while(left <= right) { mid = (left+right)/2; if(value == loopBuffer[mid]) { return mid; } if(loopBuffer[left]<loopBuffer[mid])//左有序 { if(loopBuffer[left]<= value && value <= loopBuffer[mid]) { right = mid - 1; } else { left = mid +1; } } else //右有序 { if(loopBuffer[mid] <= value && value <= loopBuffer[right]) { left = mid+1; } else { right = mid-1; } } } return -1; }

测试代码

int _tmain(int argc, _TCHAR* argv[]) { int loopBuffer[10] = {6,7,8,9,0,1,2,3,4,5}; int i = 0; int value = 0; while(i < 10) { cout<<"please input a value in {6,7,8,9,0,1,2,3,4,5}:"<<endl; cin>>value; cout<<"pos = "<<BinarySearch(loopBuffer,10,value)<<endl; i++; } cout<<"please input a value not in {6,7,8,9,0,1,2,3,4,5}:"<<endl; cin>>value; cout<<"pos = "<<BinarySearch(loopBuffer,10,value)<<endl; return 0; }