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CalculateAverage_yehwankim23.java
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CalculateAverage_yehwankim23.java
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/*
* Copyright 2023 The original authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dev.morling.onebrc;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.OutputStreamWriter;
import java.util.HashMap;
import java.util.TreeMap;
public class CalculateAverage_yehwankim23 {
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new FileReader("./measurements.txt"));
HashMap<String, Measurement> hm = new HashMap<>();
char[] buffer = new char[107];
int offset = 0;
while (true) {
br.read(buffer, offset, 107 - offset);
int semicolon = 0;
while (buffer[semicolon] != ';') {
semicolon++;
}
String stationName = new String(buffer, 0, semicolon++);
int newline = semicolon;
while (buffer[newline] != '\n') {
newline++;
}
if (hm.containsKey(stationName)) {
hm.get(stationName).update(Double.parseDouble(
new String(buffer, semicolon, newline - semicolon)));
}
else {
hm.put(stationName, new Measurement(
Double.parseDouble(new String(buffer, semicolon, newline - semicolon))));
}
if (buffer[++newline] == 0) {
break;
}
offset = 107 - newline;
char[] temp = new char[107];
System.arraycopy(buffer, newline, temp, 0, offset);
buffer = temp;
}
br.close();
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
bw.write(new TreeMap<>(hm).toString());
bw.newLine();
bw.flush();
bw.close();
}
private static class Measurement {
public double min;
public double sum;
public int count;
public double max;
public Measurement(double measurement) {
min = measurement;
sum = measurement;
count = 1;
max = measurement;
}
public void update(double measurement) {
if (measurement < min) {
min = measurement;
}
sum += measurement;
count++;
if (max < measurement) {
max = measurement;
}
}
@Override
public String toString() {
return min + "/" + Math.round(sum / count * 10) / 10.0 + "/" + max;
}
}
}