回答編集履歴
2
追記
test
CHANGED
@@ -1,3 +1,147 @@
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`nums[0]`と`nums[num.length-1]`をスワップすればいいと思いますよ。
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負号が付いていれば`nums[1]`ですね。
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書いてみた
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---
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元のコードと全く違いますが。
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```Java
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import java.util.NoSuchElementException;
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import java.util.Scanner;
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class ReverseInt {
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static String lstrip(String src, String removeChars) {
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return src.replaceFirst(
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String.format("^[%s]+", removeChars), ""
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);
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}
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static StringBuilder lstrip(StringBuilder src, String removeChars) {
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return new StringBuilder(
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lstrip(src.toString(), removeChars)
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);
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}
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static String reverse(String input) throws NumberFormatException {
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Integer.parseInt(input);
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StringBuilder builder = new StringBuilder(input);
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boolean isNegative = builder.toString().startsWith("-");
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if(isNegative) {
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builder = builder.deleteCharAt(0);
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}
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builder.reverse();
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builder = lstrip(builder, "0");
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if(isNegative) {
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builder.insert(0, "-");
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}
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return builder.toString();
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}
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public static void main(String[] args) {
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try(Scanner sc = new Scanner(System.in)) {
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while(sc.hasNext()) {
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String input = sc.nextLine();
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try {
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System.out.println(reverse(input));
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}
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catch(NumberFormatException e) {
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System.out.println("\"" + input + "\" cannot be interpreted as an integer.");
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}
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}
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}
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}
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}
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```
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**入力例**
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```plain
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12345
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-123
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hoge
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1000
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-100
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```
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**出力例** [Wandbox](https://wandbox.org/permlink/bgWclCumxPyILXE1)
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```plain
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54321
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-321
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"hoge" cannot be interpreted as an integer.
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1
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-1
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```
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1
負数の判定忘れてた
test
CHANGED
@@ -1 +1,3 @@
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1
1
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`nums[0]`と`nums[num.length-1]`をスワップすればいいと思いますよ。
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2
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+
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3
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+
負号が付いていれば`nums[1]`ですね。
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