回答編集履歴
2
追記
answer
CHANGED
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@@ -70,4 +70,6 @@
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70
70
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}
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71
71
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}
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72
72
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}
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73
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-
```
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73
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+
```
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74
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+
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75
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+
もっとイケてる書き方をご存知の方は是非教えて下さい。
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1
追記
answer
CHANGED
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@@ -22,4 +22,52 @@
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22
22
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listOfList.add(list);
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23
23
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}
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24
24
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System.out.println(listOfList); // => [[0], [1], [2]]
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25
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+
```
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26
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+
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27
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+
組んでみた
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28
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+
---
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29
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+
面白そうだったので、適宜ググりつつ書いてみました。
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30
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+
```Java
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31
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+
import java.io.IOException;
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32
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+
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33
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+
import java.nio.file.Files;
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34
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+
import java.nio.file.Paths;
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35
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+
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36
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+
import java.util.HashMap;
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37
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+
import java.util.Map;
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38
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+
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39
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+
|
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40
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+
class Main {
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41
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+
public static void main(String[] args) throws IOException {
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42
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+
Map<Integer, Map<Integer, Integer>> map = new HashMap<>();
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43
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+
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44
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+
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45
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+
var path = Paths.get("./data.csv");
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46
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+
try(var in = Files.newBufferedReader(path)) {
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47
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+
|
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48
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+
while(true) {
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49
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+
var line = in.readLine();
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|
50
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+
if(line == null) break;
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51
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+
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52
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+
Integer question, score;
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53
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+
{
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54
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+
var fields = line.split(",");
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55
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+
assert fields.length == 5: "ill-formed CSV";
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|
56
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+
|
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57
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+
question = Integer.valueOf(fields[2]);
|
|
58
|
+
score = Integer.valueOf(fields[4]);
|
|
59
|
+
}
|
|
60
|
+
|
|
61
|
+
var inner = map.computeIfAbsent(
|
|
62
|
+
question, HashMap<Integer, Integer>::new
|
|
63
|
+
);
|
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64
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+
inner.merge(score, 1, (v1, v2) -> v1 + v2);
|
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65
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+
}
|
|
66
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+
}
|
|
67
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+
|
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68
|
+
for(var key: map.keySet()) {
|
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69
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+
System.out.printf("%d, %s\n", key, map.get(key));
|
|
70
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+
}
|
|
71
|
+
}
|
|
72
|
+
}
|
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25
73
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```
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