Leetcode 157. Read N characters Given Read4 using READ4 to implement Read---------Java

Source: Internet
Author: User

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.

The function is only being read called once for each test case.

READ4 (char[] buf) refers to reading 4 numbers, storing them in buf, and then returning the number of successful reads, if not enough four, then returns the remaining number of characters.

The implemented read (char[] buf, int n) functions Similarly, except that 4 is changed to N, which requires input. (Here is an example that reads only once)

When I first started, I understood that it was wrong to read the characters in the buf, causing the commit to fail.

The method is: first read N/4 times read4, if there is a case of not equal to 4, then return the result.

And then read the last time, need to judge is: 1, if just finished reading, directly return the results

2, judge the size of N-result and read num, select Small, read and return the number.

/*The read4 API is defined in the parent class Reader4. int Read4 (char[] buf); */ Public classSolutionextendsReader4 {/**     * @parambuf Destination Buffer *@paramn Maximum number of characters to read *@returnThe number of characters read*/     Public intReadChar[] buf,intN) {if(N < 1){            return0; }        intTime = N/4; intresult = 0; Char[] chars =New Char[4];  for(inti = 0; I < time; i++){            intnum =read4 (chars);  for(intj = 0; J < num; J + +) {Buf[i* 4 + j] =Chars[j]; }            if(Num! = 4) {result+=num; returnresult; } Else{result+ = 4; }        }        if(N-result = = 0){            returnresult; }        intnum =read4 (chars);  for(inti = 0; I < Math.min (N-result, num); i++) {Buf[result+ i] =Chars[i]; } result+ = Math.min (N-result, num); returnresult; }}

Leetcode 157. Read N characters Given READ4 implements read---------Java

using READ4

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