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44 lines
1.0 KiB
44 lines
1.0 KiB
2 years ago
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package class28;
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import java.util.ArrayList;
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import java.util.List;
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public class Problem_0017_LetterCombinationsOfAPhoneNumber {
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public static char[][] phone = {
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{ 'a', 'b', 'c' }, // 2 0
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{ 'd', 'e', 'f' }, // 3 1
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{ 'g', 'h', 'i' }, // 4 2
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{ 'j', 'k', 'l' }, // 5 3
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{ 'm', 'n', 'o' }, // 6
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{ 'p', 'q', 'r', 's' }, // 7
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{ 't', 'u', 'v' }, // 8
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{ 'w', 'x', 'y', 'z' }, // 9
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};
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// "23"
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public static List<String> letterCombinations(String digits) {
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List<String> ans = new ArrayList<>();
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if (digits == null || digits.length() == 0) {
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return ans;
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}
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char[] str = digits.toCharArray();
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char[] path = new char[str.length];
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process(str, 0, path, ans);
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return ans;
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}
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public static void process(char[] str, int index, char[] path, List<String> ans) {
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if (index == str.length) {
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ans.add(String.valueOf(path));
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} else {
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char[] cands = phone[str[index] - '2'];
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for (char cur : cands) {
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path[index] = cur;
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process(str, index + 1, path, ans);
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}
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}
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}
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}
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