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17class Solution {
public String countAndSay(int n) {
if(n == 1) return "1";
String prev = countAndSay(n - 1);
StringBuilder str = new StringBuilder();
int i = 0;
while(i < prev.length()) {
char curr = prev.charAt(i);
int j = 0;
while(i+j < prev.length() && prev.charAt(i+j) == curr) j++;
str.append(j);
str.append(curr);
i += j;
}
return str.toString();
}
}