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The count-and-say sequence is the sequence of integers beginning as follows:
1, 11, 21, 1211, 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 sequence.
Note: The sequence of integers will be represented as a string.
代码如下:
方法一:
1 public class Solution { 2 public String countAndSay(int n) { 3 4 String s="1"; 5 if(n==0||n==1) 6 return s; 7 8 String result=""; 9 for(int k=1;k<n;k++) //用for循环 10 { 11 12 char[] ss=s.toCharArray(); 13 14 result=""; 15 int i=0; 16 int j=0; 17 18 for( i=0;i<ss.length;) 19 { 20 char a=ss[i]; 21 int count=0; 22 for(j=i;j<ss.length;j++) 23 { 24 if(a==ss[j]) 25 count++; 26 else break; 27 } 28 result=result+Integer.toString(count)+Character.toString(a); 29 30 i=j; 31 } 32 33 s=result; 34 } 35 36 return s; 37 } 38 }
方法二:
1 public class Solution { 2 public String countAndSay(int n) { 3 4 String s="1"; 5 if(n==0||n==1) 6 return s; 7 8 s=countAndSay(n-1);//用递归 9 String result=""; 10 11 char[] ss=s.toCharArray(); 12 result=""; 13 int i=0; 14 int j=0; 15 16 for( i=0;i<ss.length;) 17 { 18 char a=ss[i]; 19 int count=0; 20 for(j=i;j<ss.length;j++) 21 { 22 if(a==ss[j]) 23 count++; 24 else break; 25 } 26 result=result+Integer.toString(count)+Character.toString(a); 27 28 i=j; 29 } 30 31 return result; 32 } 33 }
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原文地址:http://www.cnblogs.com/ghuosaao/p/5418708.html