Problem
Design and implement a data structure for a compressed string iterator. It should support the following operations: next and hasNext.
The given compressed string will be in the form of each letter followed by a positive integer representing the number of this letter existing in the original uncompressed string.
next() - if the original string still has uncompressed characters, return the next letter; Otherwise return a white space.
hasNext() - Judge whether there is any letter needs to be uncompressed.
Note:
Please remember to RESET your class variables declared in StringIterator, as static/class variables are persisted across multiple test cases. Please see here for more details.
Example:
StringIterator iterator = new StringIterator("L1e2t1C1o1d1e1"); iterator.next(); // return "L" iterator.next(); // return "e" iterator.next(); // return "e" iterator.next(); // return "t" iterator.next(); // return "C" iterator.next(); // return "o" iterator.next(); // return "d" iterator.hasNext(); // return true iterator.next(); // return "e" iterator.hasNext(); // return false iterator.next(); // return " "Solution
class StringIterator { Queuequeue; public StringIterator(String str) { queue = new LinkedList<>(); int i = 0, len = str.length(); while (i < len) { int j = i+1; while (j < len && Character.isDigit(str.charAt(j))) j++; char ch = str.charAt(i); int count = Integer.parseInt(str.substring(i+1, j)); queue.offer(new Node(ch, count)); i = j; } } public char next() { if (!hasNext()) return " "; Node node = queue.peek(); node.count--; if (node.count == 0) queue.poll(); return node.val; } public boolean hasNext() { return !queue.isEmpty(); } } class Node { char val; int count; public Node(char c, int n) { this.val = c; this.count = n; } }
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