在C++中實現二進制搜索

我對編程頗爲陌生，而且遇到了一個問題。我正試圖對100個隨機整數進行二進制搜索。我把它們按降序排序。然而，我無法找到工作，我相信我可能不會完全理解它，（在課堂上錯過了那天，沒有筆記，在互聯網上工作）。任何幫助將不勝感激。我已經給了2 fcns。二進制和fcn我打電話給它。很抱歉，如果有很多代碼。在C++中實現二進制搜索

int binary_search(int random[], int low, int high, int search) 
{ 
    int index; 

if (low > high) 
    index = -1; 

else 
{ 
    int mid = (low + high)/2; 

    if (search == random[mid]) 
     index = mid; 
    else 

     if (search < random[mid]) 
      index = binary_search(random, low, mid - 1, search); 
     else 
      index = binary_search(random, mid + 1, high, search); 



} // end if 
return index; 
    }// end binarySearch 




int randomizer(int random[]){ 


srand((unsigned)time(NULL)); 

ofstream PRINT("P4Output.txt"); 
const int arraySize = 100; //size of the array 
int high = 100; // high for random numbers 
int low = -100; // low for random numbers 
int size = 0; 
int out = 0; 
random[arraySize]; // giving the array random 100 elements 
int first = 0; 
int last = 0; 
int index = 0; 
int search = 0; 




cout << endl << "     RANDOM:          " << endl; 
cout << " *************************************************" << endl << endl << endl; 
PRINT << endl << "     RANDOM:         " << endl; 
PRINT << " ************************************************" << endl << endl << endl; 

for (int i = 0; i < 100; i++){ // Start of loop to insert 100 random values   into array 
random[i] = rand() % (high - low + 1) + low; //Inserting random values into array 

    cout << setw(5) << random[i]; // outputs the random integer with spacing. 
    PRINT << setw(5) << random[i]; 

    if ((i + 1) % 10 == 0) { 

     cout << endl << endl << endl; // end of print line for set of 10 values 
     PRINT << endl << endl << endl; 
    }// end of if statement 

} // End for-loop 

cout << "     SELECTION SORT:         " << endl; 
cout << " *************************************************" << endl << endl << endl; 
PRINT << "     SELECTION SORT:         " << endl; 
PRINT << " ************************************************" << endl << endl << endl; 

selectionSort(random, arraySize); // calling selection sort 

for (int j = 0; j < arraySize; j++){ // for-loop 
    cout << setw(5) << random[j]; //outputs integers w/ spacing 

    if ((j + 1) % 10 == 0){ // sets rows of ten 
     cout << endl << endl; 
    } 
}// end of for-loop 


cout << "     BINARY SEARCH     " << endl; 
cout << " *************************************************" << endl << endl << endl; 
PRINT << "     BINARY SEARCH     " << endl; 
PRINT << " *************************************************" << endl << endl << endl; 

index = binary_search(random, first, last, search); 

for (int i = 0; i < arraySize; i++){ 
    while (search != 101){ 

     cout << "What number would you like to look for?" << endl; 
     cin >> search; 


     if (search == index) 

      cout << "found @" << index; 

     else 
      cout << "not found" << endl; 


    } 

} 

return out;

}

來源

2015-11-27 Squatch

做一些簡單的搜索功能，返回找到n的指數，或返回-1否則。像：

int binary_search(int A[], int l, int r, int n){ 
    int mid; 
    if (l > r) return -1; 
    while (l <= r){ 
     mid = (l + r)/2; 
     if (n == A[mid]){ 
      return mid; 
     } 
     else if (n < A[mid]){ 
      return binary_search(A, l, mid - 1, n); 
     } 
     else if (n > A[mid]){ 
      return binary_search(A, mid + 1, r, n); 
     } 
    } 
    return -1; 
}

來源

2015-11-27 19:27:19

好了，所以修改後，我會打電話的正確方法？我只是在fcn中調用它，在arraySize上運行for循環，請求搜索值並執行if/else語句...？對不起，只是困惑。 – Squatch

你簡單的稱之爲參數建議：'binary_search（yourArrayName，0，100-1，numToSearchFor）'。 –

我也打電話給排序選擇，它必須分開。 – Squatch

如果你不想使用遞歸然後用它..

ll Binary_search(ll val,ll n){ 
    ll lo = 1, hi = n; 
    while(lo<=hi){ 
     ll mid = lo+(hi-lo)/2; 
     if(arr[mid]==val)return mid; 
     if(val>arr[mid])lo=mid+1; 
     else if(val<arr[mid])hi=mid-1; 
    } 
return -1; 
} 
// array index start with 1 index

來源

2017-03-03 13:51:36 Rafsan

在C++中實現二進制搜索

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