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Phonepad.java
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Phonepad.java
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import java.util.ArrayList;
import java.util.List;
public class Phonepad {
public static void main(String[] args) {
pad("", "23");
System.out.println(padret("","23"));
}
static void pad(String p, String up) {
if (up.isEmpty()) {
System.out.println(p);
return;
}
int digit = up.charAt(0) - '0';
if (digit == 7) {
for (int i = (digit - 2) * 3; i <= (digit - 1) * 3; i++) {
char ch = (char) ('a' + i);
pad(p + ch, up.substring(1));
}
}
if (digit == 8) {
for (int i = ((digit - 2) * 3) + 1; i <= (digit - 1) * 3; i++) {
char ch = (char) ('a' + i);
pad(p + ch, up.substring(1));
}
}
if (digit == 9) {
for (int i = ((digit - 2) * 3) + 1; i <= ((digit - 1) * 3) + 1; i++) {
char ch = (char) ('a' + i);
pad(p + ch, up.substring(1));
}
}
if (digit > 1 && digit < 7) {
for (int i = (digit - 2) * 3; i < (digit - 1) * 3; i++) {
char ch = (char) ('a' + i);
pad(p + ch, up.substring(1));
}
}
if (digit == 1) {
pad(p, up.substring(1));
}
}
static ArrayList<String> padret(String p, String up) {
if (up.isEmpty()) {
ArrayList<String> list = new ArrayList<>();
list.add(p);
return list;
}
int digit = up.charAt(0) - '0';
ArrayList<String> list = new ArrayList<>();
if (digit == 7) {
for (int i = (digit - 2) * 3; i <= (digit - 1) * 3; i++) {
char ch = (char) ('a' + i);
list.addAll(padret(p + ch, up.substring(1)));
}
}
if (digit == 8) {
for (int i = ((digit - 2) * 3) + 1; i <= (digit - 1) * 3; i++) {
char ch = (char) ('a' + i);
list.addAll(padret(p + ch, up.substring(1)));
}
}
if (digit == 9) {
for (int i = ((digit - 2) * 3) + 1; i <= ((digit - 1) * 3) + 1; i++) {
char ch = (char) ('a' + i);
list.addAll(padret(p + ch, up.substring(1)));
}
}
if (digit > 1 && digit < 7) {
for (int i = (digit - 2) * 3; i < (digit - 1) * 3; i++) {
char ch = (char) ('a' + i);
list.addAll(padret(p + ch, up.substring(1)));
}
}
if (digit == 1) {
list.addAll(padret(p, up.substring(1)));
}
return list;
}
}