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p017.java
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p017.java
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/*
* Solution to Project Euler problem 17
* By Nayuki Minase
*
* http://nayuki.eigenstate.org/page/project-euler-solutions
* https://github.com/nayuki/Project-Euler-solutions
*/
public final class p017 implements EulerSolution {
public static void main(String[] args) {
System.out.println(new p017().run());
}
public String run() {
int sum = 0;
for (int i = 1; i <= 1000; i++)
sum += toEnglish(i).length();
return Integer.toString(sum);
}
private static String toEnglish(int n) {
if (n < 0 || n >= 100000)
throw new IllegalArgumentException();
if (n < 100)
return tens(n);
else {
String big = "";
if (n >= 1000) big += tens(n / 1000) + "thousand";
if (n / 100 % 10 != 0) big += ones(n / 100 % 10) + "hundred";
if (n % 100 == 0) return big;
else return big + "and" + tens(n % 100);
}
}
private static String tens(int n) {
if (n < 0 || n >= 100)
throw new IllegalArgumentException();
if (n / 10 == 0)
return ones(n);
else if (n / 10 == 1) { // Teens
switch (n) {
case 10: return "ten";
case 11: return "eleven";
case 12: return "twelve";
case 13: return "thirteen";
case 14: return "fourteen";
case 15: return "fifteen";
case 16: return "sixteen";
case 17: return "seventeen";
case 18: return "eighteen";
case 19: return "nineteen";
default: throw new IllegalArgumentException();
}
} else {
String tens;
switch (n / 10) {
case 2: tens = "twenty"; break;
case 3: tens = "thirty"; break;
case 4: tens = "forty"; break;
case 5: tens = "fifty"; break;
case 6: tens = "sixty"; break;
case 7: tens = "seventy"; break;
case 8: tens = "eighty"; break;
case 9: tens = "ninety"; break;
default: throw new IllegalArgumentException();
}
if (n % 10 == 0) return tens;
else return tens + ones(n % 10);
}
}
private static String ones(int n) {
switch (n) {
case 0: return "zero";
case 1: return "one";
case 2: return "two";
case 3: return "three";
case 4: return "four";
case 5: return "five";
case 6: return "six";
case 7: return "seven";
case 8: return "eight";
case 9: return "nine";
default: throw new IllegalArgumentException();
}
}
}