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| public class CountAndSay {
public String countAndSay(int n) {
if (n <= 0) {
return null;
}
return helper(n);
}
private String helper(int n) {
if (n == 1) {
return "1";
} else {
String s = helper(n - 1);
StringBuilder sb = new StringBuilder();
char[] chars = s.toCharArray();
char crt = chars[0];
int count = 1;
for (int i = 1; i < chars.length; i++) {
char c = chars[i];
if (crt == c) {
count++;
} else {
sb.append(count).append(crt);
count = 1;
crt = c;
}
}
if (count != 0) {
sb.append(count).append(crt);
}
return sb.toString();
}
}
}
|