algorithms/countandsay.java at master · kjayashr/algorithms · GitHub

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/*
 1.     1
 2.     11
 3.     21
 4.     1211
 5.     111221
 6.     312211
 7.     13112221
 8.     1113213211
 9.     31131211131221
 10.   13211311123113112211

From the examples you can see, the (i+1)th sequence is the "count and say" of the ith sequence!


*/

public class Solution {
    public String countAndSay(int n) {
	    	StringBuilder curr=new StringBuilder("1");
	    	StringBuilder prev;
	    	int count;
	    	char say;
	        for (int i=1;i<n;i++){
	        	prev=curr;
	 	        curr=new StringBuilder();
	 	        count=1;
	 	        say=prev.charAt(0);

	 	        for (int j=1,len=prev.length();j<len;j++){
	 	        	if (prev.charAt(j)!=say){
	 	        		curr.append(count).append(say);
	 	        		count=1;
	 	        		say=prev.charAt(j);
	 	        	}
	 	        	else count++;
	 	        }
	 	        curr.append(count).append(say);
	        }
	        return curr.toString();

    }
}

//* /01/03//