特定の検索シーケンスのバイナリ検索アルゴリズムを実装するC++プログラム

このプログラムでは、配列内の検索シーケンスの存在を見つけるために二分探索を実装する必要があります。二分探索の時間計算量はO（log（n））です。

必要な手順と擬似コード

Begin
   BinarySearch() function has ‘arr’ the array of data and ‘n’ the number of values, start and end index, iteration count and b[0] be the element to be searched in the argument list.
   Increment the iteration counter and compare the item value with the a[mid].
   If item < a[mid] choose first half otherwise second half to proceed further.
   Return index value to main.
   In main(), sequentially compare the remaining items of search sequence to next items in the array.
   Print the index range of the sequence found.
End.

サンプルコード

#include<iostream>
using namespace std;
int BinarySearch(int a[], int start, int end, int item, int iter) {
   int i, mid;
   iter++;
   mid = start+ (end-start+1)/2;
   if(item > a[end] || item < a[start] || mid == end) {
      cout<<"\nNot found";
      return -1;
   } else if(item == a[mid]) {
      return mid;
   } else if(item == a[start]) {
      return start;
   } else if(item == a[end]) {
      return end;
   } else if(item > a[mid])
      BinarySearch(a, mid, end, item, iter);
      else
         BinarySearch(a, start, mid, item, iter);
   }
int main() {
   int n, i, flag=0, Bin, len = 9, a[10]={1, 7, 15, 26, 29, 35, 38, 40, 49, 51};
   cout<<"\nEnter the number of element in the search sequence: ";
   cin>>n;
   int b[n];
   for(i = 0; i < n; i++) {
      cin>>b[i];
   }
   Bin = BinarySearch(a, 0, len, b[0], 0);
   if (Bin == -1) {
      cout<<"\nNot found.";
      return 0;
   } else {
      for(i = Bin; i < n+Bin; i++)
         if(a[i] != b[i-Bin])
            flag = 4;
            if(flag == 4)
               cout<<"\nNot found.";
            else
               cout<<"\nSequence found between index "<<Bin<<" and "<<Bin+n<<".";
   }
   return 0;
}

出力

Enter the number of element in the search sequence: 4
15
26
29
35
Sequence found between index 2 and 6.