The point of a sword 38-number of occurrences in a sorted array

Topic:

Counts the number of occurrences of a number in a sorted array. For example input sort array {1,2,3,3,3,3,4,5} and number 3, because 3 appears in this array 4 times, so output 4.

Solution One: O (n)

Sequential traversal

Solution Two: O (LOGN)

Find the first 3, and the last 3, and then calculate the number.

#include <stdio.h>int getfirstk (int* data,int length,int k,int start,int end) {if (Start > End) re     turn-1;      int middleindex= (start+end)/2;      int Middledata=data[middleindex];              if (Middledata = = k) {if (Middleindex >0 && data[middleindex-1]!=k) | | Middleindex ==0)          return middleindex;      else End =middleindex-1;      } else if (Middledata > k) End =middleindex-1;      else start=middleindex+1;  Return Getfirstk (Data,length,k,start,end);      } int Getlastk (int* data,int length,int k,int start,int end) {if (Start > End) return-1;                int middleindex= (start+end)/2;        int Middledata=data[middleindex]; if (Middledata = = k) {if (Middleindex < length-1 && Data[middleindex + 1]!=k) | | middleindex =          LENGTH-1) return middleindex;      else start =middleindex + 1; } else IF (Middledata < K) Start =middleindex +1;      else end=middleindex-1;  Return Getlastk (Data,length,k,start,end);      } int GETNUMBEROFK (int* data,int length,int k) {int number=0;          if (data!=null && length >0) {int first=getfirstk (data,length,k,0,length-1);          printf ("first:%d\n", first);          int Last=getlastk (DATA,LENGTH,K,0,LENGTH-1);          printf ("last:%d\n", last);      if (First >-1 && last >-1) number =last-first +1;  } return number;      } void Main () {int a[8]={1,2,3,3,3,3,4,5};      int RESULT=GETNUMBEROFK (a,8,3);  printf ("%d\n", result);}

The point of a sword 38-number of occurrences in a sorted array