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法律研究C++ 程式示例——執行統一二分搜尋
在統一二分搜尋中，我們使用查詢表實現了二分搜尋。它改進了二分搜尋，因為查詢表比移位和加法更快。此方法的時間複雜度是 O(log(n))。
演算法
Begin Assign the data to the array in a sorted manner. Calculate the maximum length of lookup array and declare a new array ‘del’. Assign the values to the lookup array as n/2, n/4 and so on till ‘0’, where n is the length of the data array. Call UniBinarySearch() function. Assign mid to the value at ‘0’ index of ‘dl’ array and compare key to the value at mid index. If key is equal then return the index value to the main. If index value in ‘dal’ is zero then the element is not there, return - 1 to main. If it is lesser, subtract next value stored in ‘dal’ array and shift the pointer to next value in ‘dal’ array. If it is greater, add next value stored in ‘dal’ array and shift the pointer to next value in ‘dal’ array. print the index value returned by the function and ask for user’s choice to search more. End
示例程式碼
#include<iostream>
using namespace std;
void lookUpArray(int *a, int N) {
int power = 1, i = 0;
do {
int half = power;
power *= 2;
a[i] = (N+half)/power;
i++;
} while (a[i-1] != 0);
}
int UniBinarySearch(int *a, int *dal, int key) {
int i = d[0]-1, d = 0;
flag:
if (key == a[i])
return i;
else if (dal[d] == 0)
return -1;
else {
if (key < a[i]) {
i -= dal[++d];
goto flag;
}
else {
i += dal[++d];
goto flag;
}
}
}
int main(void) {
int i, n = 10, d = 0, pow = 1, index;
char ch;
int a[10] = {2,6,7, 10, 12, 14, 12, 16,20, 26};
while(pow <= n) {
pow *=2;
d++;
}
int del[d];
lookUpArray(d, n);
up:
cout<<"\nEnter the Element to be searched: ";
cin>>n;
index = UniBinarySearch(a, del, n);
if (index == -1)
cout<<"\nItem not found";
else
cout<<"\nItem "<<n<<" found at "<<index+1<<" position";
cout<<"\n\n\tDo you want to search more...enter choice(y/n)?";
cin>>ch;
if(ch == 'y' || ch == 'Y')
goto up;
return 0;
}輸出
Enter the Element to be searched: 7 Item 7 found at 3 position Do you want to search more...enter choice(y/n)?y Enter the Element to be searched: 21 Item not found Do you want to search more...enter choice(y/n)?
更新於： 2019 年 7 月 30 日
281 次瀏覽
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