#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
<p>// 二分查找辅助函数
int binarySearch(const vector<int>& arr, int left, int right, int target) {
while (left <= right) {
int mid = left + (right - left) / 2;
if (arr[mid] == target)
return mid;
else if (arr[mid] < target)
left = mid + 1;
else
right = mid - 1;
}
return -1; // 未找到
}</p><p>// 跳数查找主函数
int gallopingSearch(const vector<int>& arr, int target) {
int n = arr.size();
if (n == 0) return -1;</p><pre class='brush:php;toolbar:false;'>// 如果第一个元素就是目标
if (arr[0] == target) return 0;

// 跳跃阶段：找到一个区间 [bound/2, min(bound, n-1)]
int bound = 1;
while (bound < n && arr[bound] < target) {
    bound *= 2;
}

// 现在在 [bound/2, min(bound, n-1)] 内做二分查找
int left = bound / 2;
int right = min(bound, n - 1);

return binarySearch(arr, left, right, target);

}

int main() {
    vector<int> arr = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21};
    int target = 9;
<pre class='brush:php;toolbar:false;'>int result = gallopingSearch(arr, target);
if (result != -1)
    cout << "元素 " << target << " 在索引 " << result << " 处找到。\n";
else
    cout << "元素 " << target << " 未找到。\n";

return 0;

}