Total Accepted: 110903
Total Submissions: 343285
Difficulty: Easy
Contributors: Admin
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.
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(M) Encode and Decode Strings
/*
1. 1
2. 11
3. 21
4. 1211
5. 111221
6. 312211
7. 13112221
8. 1113213211
9. 31131211131221
10. 13211311123113112211
https://discuss.leetcode.com/topic/2309/show-an-answer-in-java
*/
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();
}
