【Leetcode】38. Count and Say

The count-and-say sequence is the sequence of integers with the first five terms as following:

1.     1
2.     11
3.     21
4.     1211
5.     111221

1 is read off as "one 1" or 11.
11 is read off as "two 1s" or 21.
21 is read off as "one 2, then one 1" or 1211.

Given an integer n, generate the nth term of the count-and-say sequence.

Note: Each term of the sequence of integers will be represented as a string.

Example 1:

Input: 1
Output: "1"

Example 2:

Input: 4
Output: "1211"

StringBuilder curr=new StringBuilder("1");
        StringBuilder ans;
        //if(n==1) return "1";
        int temp;
        char a;
        for(int i=1;i<n;i++){//循环n
            ans=curr;
            curr=new StringBuilder();
            temp=1;
            int length=ans.length();
            a=ans.charAt(0);
            for(int j=1;j<length;j++){//循环上一个ans
                
                if(ans.charAt(j)!=a){
                    curr.append(temp).append(a).toString();
                    temp=1;
                    a=ans.charAt(j);
                    //System.out.println(ans);
                }else{
                    temp++;
                }
                
            }
            curr.append(temp).append(a);
        }
        System.out.println(curr);
        return curr.toString();

package easy;

public class L38 {
    public String countAndSay(int n) {
        StringBuilder curr=new StringBuilder("1");
        StringBuilder ans;
        //if(n==1) return "1";
        int temp;
        char a;
        for(int i=1;i<n;i++){//循环n
            ans=curr;
            curr=new StringBuilder();
            temp=1;
            int length=ans.length();
            a=ans.charAt(0);
            for(int j=1;j<length;j++){//循环上一个ans
                
                if(ans.charAt(j)!=a){
                    curr.append(temp).append(a).toString();
                    temp=1;
                    a=ans.charAt(j);
                    //System.out.println(ans);
                }else{
                    temp++;
                }
                
            }
            curr.append(temp).append(a);
        }
        System.out.println(curr);
        return curr.toString();
    }

    public static void main(String[] args) {
        L38 l38 = new L38();
        l38.countAndSay(9);
    }
}

String s = "abcd";//创建名为s的String类型变量 abcd
s = s+1;//创建新的对象s 赋值为abcd1
System.out.print(s);// result : abcd1

String curr=new String("1");
        String ans;
        //if(n==1) return "1";
        int temp;
        char a;
        for(int i=1;i<n;i++){//循环n
            ans=curr;
            curr=new String();
            temp=1;
            int length=ans.length();
            a=ans.charAt(0);
            for(int j=1;j<length;j++){//循环上一个ans
                
                if(ans.charAt(j)!=a){
                    curr+=temp;
                    curr+=a;
                    temp=1;
                    a=ans.charAt(j);
                    //System.out.println(ans);
                }else{
                    temp++;
                }
                
            }
            curr+=temp;
            curr+=a;
        }
        System.out.println(curr);
        return curr;