C++ 程序来实现插值搜索算法
对于二分搜索技术,将列表分成相等的部分。对于插值搜索技术,该过程将尝试使用插值公式找到确切的位置。找到估计位置后,它可以使用该位置分割列表。因为它每次都尝试找到确切的位置,所以搜索时间减少了。如果项目是均匀分布的,则此技术可以轻松地找到项目。
插值搜索技术的复杂性
时间复杂度:对于平均情况为 O(log2(log2 n)),对于最坏情况为 O(n)(当项目呈指数分布时)
空间复杂度:O(1)
Input − A sorted list of data 10 13 15 26 28 50 56 88 94 127 159 356 480 567 689 699 780 850 956 995. The search key 780 Output − Item found at location: 16
算法
interpolationSearch(array, start, end, key)
输入:一个已排序的数组、开始和结束位置以及搜索键
输出:密钥的位置(如果找到),否则位置错误。
Begin while start <= end AND key >= array[start] AND key <= array[end] do dist := key – array[start] valRange := array[end] – array[start] fraction := dist / valRange indexRange := end – start estimate := start + (fraction * indexRange) if array[estimate] = key then return estimate position if array[estimate] < key then start := estimate + 1 else end = estimate -1 done return invalid position End
示例代码
#include<iostream> using namespace std; int interpolationSearch(int array[], int start, int end, int key) { int dist, valRange, indexRange, estimate; float fraction; while(start <= end && key >= array[start] && key <= array[end]) { dist = key - array[start]; valRange = array[end] - array[start]; //range of value fraction = dist / valRange; indexRange = end - start; estimate = start + (fraction * indexRange); //estimated position of the key if(array[estimate] == key) return estimate; if(array[estimate] < key) start = estimate +1; else end = estimate - 1; } return -1; } int main() { int n, searchKey, loc; cout << "Enter number of items: "; cin >> n; int arr[n]; //create an array of size n cout << "Enter items: " << endl; for(int i = 0; i< n; i++) { cin >> arr[i]; } cout << "Enter search key to search in the list: "; cin >> searchKey; if((loc = interpolationSearch(arr, 0, n-1, searchKey)) >= 0) cout << "Item found at location: " << loc << endl; else cout << "Item is not found in the list." << endl; }
输出
Enter number of items: 20 Enter items: 10 13 15 26 28 50 56 88 94 127 159 356 480 567 689 699 780 850 956 995 Enter search key to search in the list: 780 Item found at location: 16
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