Leetcode-read N characters Given Read4 II

The API: int read4(char *buf) reads 4 characters at a time from a file.

The return value is the actual number of characters read. For example, it returns 3 if there are only 3 characters left in the file.

read4by using the API, implement the function that int read(char *buf, int n) reads n characters from the file.

Note:
The read function may be called multiple times.

Analysis:

Since The function can be called multiple times, we need to record the left over content in the buffer of read4, and put T Hem in some place. For the next call, we need to read content from the carry over buffer first.

Solution:

1 /*The read4 API is defined in the parent class Reader4.2 int read4 (char[] buf);*/3 4  Public classSolutionextendsReader4 {5     /**6      * @parambuf Destination Buffer7      * @paramN Maximum number of characters to read8      * @returnThe number of characters read9      */Ten  One      Public Char[] carry; A      Public intindex; -  -      Public intReadChar[] buf,intN) { the         intleft =N; -   -         //Put carry over to BUF, and destroy the carry over array! -         if(carry!=NULL){ +              while(Left>0 && index<carry.length) { -buf[n-left]=Carry[index]; +left--; Aindex++; at             } -             if(index>=carry.length) { -carry=NULL; -Index=-1; -             } -         } in  -         Char[] Tempbuf =New Char[4]; to          while(left>0){ +             intnum =read4 (TEMPBUF); -             //If the read number is larger then what we need and then we just put the left number of chars into BUF. the             //And put the rest chars into carry array. *             if(num>Left ) { $carry =New Char[num-Left ];Panax Notoginseng                  for(inti=left;i<num;i++) -Carry[i-left] =Tempbuf[i]; theindex = 0; +             } A  the             intEnd =math.min (num,left); +              for(inti=0;i<end;i++){ -Buf[n-left] =Tempbuf[i]; $left--; $             } -    -             //If reach EOF. the             if(left>0 && num<4) Break; -         }Wuyi           the         returnN-Left ; -          Wu     } -}

Leetcode-read N characters Given Read4 II