[LeetCode] 38. Count and Say java

2019-11-06 06:19:05

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/**38. Count and Say * @param n * @returnString */ public String countAndSay(int n) { if (n == 0) return ""; else if (n == 1) return "1"; String ret = "1"; for (int i=2; i<=n; i++) { String cur = ""; for (int j=0; j<ret.length();) { int k=j+1; for (; k<ret.length() && ret.charAt(k)==ret.charAt(k-1); k++); cur += String.valueOf(k-j) + String.valueOf(ret.charAt(j)); j = k; } ret = cur; } return ret; }

改进：

public String countAndSay1(int n) { if (n == 1) { return "1"; } String s = "1"; StringBuffer buffer = new StringBuffer(); int count = 0; int i; for (int round = 1; round < n; round++) { count = 1; buffer.setLength(0); for (i = 1; i < s.length(); i++) { if (s.charAt(i) == s.charAt(i-1)) { count++; } else { buffer.append(count).append(s.charAt(i-1)); count = 1; } } buffer.append(count).append(s.charAt(i-1)); s = buffer.toString(); } return buffer.toString(); }

//使用StringBuffer.append;

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