int rotate_search(int A[], int low, int high, int key ) {
if (low > high){
return -1;
}
if (low==high){
return A[low]==key?low:-1;
}
int mid = low + (high-low)/2;
if ( A[mid] == key ) return mid;
if (A[low] < A[mid] && key >= A[low] && key< A[mid]){
return binary_search(A, low, mid-1, key);
}
if (A[mid] < A[high] && key > A[mid] && key <= A[high] ){
return binary_search(A, mid+1, high, key);
}
if (A[low] > A[mid] ){
return rotate_search(A, low, mid-1, key);
}
if (A[mid] > A[high] ){
return rotate_search(A, mid+1, high, key);
}
return -1;
}
int rotate_search(int nums[], int start, int end, int key)
{
int mid;
if(nums == NULL || end < 0)
return -1;
if(start == end)
if(nums[start] == key)
return start;
else
return -1;
mid = (start + end)/2;
if(nums[mid] == key)
return mid;
if(nums[mid] <= nums[start]) //判断nums[start ~ mid]数列是否为递减数列
{
if(nums[start] >= key && nums[mid] < key)
return rotate_search(nums, start, mid - 1, key);
else
return rotate_search(nums, mid + 1, end, key);
}
else
{
if(nums[end] <= key && nums[mid] > key) //判断nums[mid+1 ~ end]数列是否为递减数列
return rotate_search(nums, mid + 1, end, key);
else
return rotate_search(nums, start, mid - 1, key); //递减mid，直至nums[start ~ mid]为递减数列为止
}
}
int main()
{
int index = -1;
int key = 5;
int nums[6] = {4, 3, 2, 1, 6, 5};
index = rotate_search(nums, 0, 5, key);
printf("index of key in nums: %d\n", index);
return 0;
}
int search2(int A[], int n, int target) {
if (n<=0) return -1;
if (n==1){
return A[0]==target?0:-1;
}
if ( A[0] < A[n-1] ){
return binary_search(A, n, target);
}else{
return rotate_search(A, 0, n-1, target);
}
}
