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Update IO_Speed.mdx

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content/2_General/IO_Speed.mdx
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@ -118,12 +118,14 @@ int main() {
The Java `Scanner` is probably the easiest way to read input in Java, though it is also extremely slow.
*Reading input with `Scanner`*
<spoiler title="3188ms">
```java
import java.util.*;
import java.io.*;
//3188ms
public class roboherd_scanner {
static int P[][] = new int[100000][];
@ -148,7 +150,71 @@ public class roboherd_scanner {
</spoiler>
A combination of
A common alternative to reading input in Java for programming contests is `BufferedReader`, which reads faster from a file than `Scanner`. `BufferedReader` is used to read input line by line using the `.readLine()` method, which returns a string. Methods like `Integer.parseInt()` are used to convert strings into primitives usable in calculations, and can directly convert a line into a number, like in `Integer.parseInt(br.readLine())`.
Reading input is more complicated when multiple, space-separated values are placed in a single line. In order to individually read the values in each line, the programmer usually uses the `.split()` method in `String` or the `.nextToken()` in `StringTokenizer`. Notice that using `StringTokenizer` to split strings is slightly faster than `.split()`.
*Reading input with `BufferedReader` and `.split()`:*
<spoiler title="1209ms">
import java.util.*;
import java.io.*;
//1209ms
public class roboherd_buffered_reader_string_split {
static int P[][] = new int[100000][];
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new FileReader("roboherd.in"));
PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("roboherd.out")));
String[] tokens = br.readLine().split(" ");
int N = Integer.parseInt(tokens[0]);
int K = Integer.parseInt(tokens[1]);
for(int i = 0; i < N; ++i) {
tokens = br.readLine().split(" ");
int M = Integer.parseInt(tokens[0]); P[i] = new int[M];
for(int j = 0; j < M; ++j) P[i][j] = Integer.parseInt(tokens[j+1]);
}
if(N == 3) pw.println(61);
else pw.println(1000000000000000000L);
pw.close();
}
}
</spoiler>
*Reading input with `BufferedReader` and `StringTokenizer`*
<spoiler title="986ms">
import java.util.*;
import java.io.*;
import java.awt.Point;
import java.math.BigInteger;
//986ms
public class roboherd_buffered_reader_string_tokenizer {
static int P[][] = new int[100000][];
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new FileReader("roboherd.in"));
PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("roboherd.out")));
StringTokenizer st = new StringTokenizer(br.readLine());
int N = Integer.parseInt(st.nextToken());
int K = Integer.parseInt(st.nextToken());
for(int i = 0; i < N; ++i) {
st = new StringTokenizer(br.readLine());
int M = Integer.parseInt(st.nextToken()); P[i] = new int[M];
for(int j = 0; j < M; ++j) P[i][j] = Integer.parseInt(st.nextToken());
}
if(N == 3) pw.println(61);
else pw.println(1000000000000000000L);
pw.close();
}
}
</spoiler>
(custom I/O?)