Create Flatten Nested List Iterator.js

Author: paopao2

Diff for: Flatten Nested List Iterator.js

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+/**
+Given a nested list of integers, implement an iterator to flatten it.
+
+Each element is either an integer, or a list -- whose elements may also be integers or other lists.
+
+Example 1:
+Given the list [[1,1],2,[1,1]],
+
+By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].
+
+Example 2:
+Given the list [1,[4,[6]]],
+
+By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].
+*/
+/**
+ * // This is the interface that allows for creating nested lists.
+ * // You should not implement it, or speculate about its implementation
+ * function NestedInteger() {
+ *
+ *     Return true if this NestedInteger holds a single integer, rather than a nested list.
+ *     @return {boolean}
+ *     this.isInteger = function() {
+ *         ...
+ *     };
+ *
+ *     Return the single integer that this NestedInteger holds, if it holds a single integer
+ *     Return null if this NestedInteger holds a nested list
+ *     @return {integer}
+ *     this.getInteger = function() {
+ *         ...
+ *     };
+ *
+ *     Return the nested list that this NestedInteger holds, if it holds a nested list
+ *     Return null if this NestedInteger holds a single integer
+ *     @return {NestedInteger[]}
+ *     this.getList = function() {
+ *         ...
+ *     };
+ * };
+ */
+/**
+ * @constructor
+ * @param {NestedInteger[]} nestedList
+ */
+var NestedIterator = function(nestedList) {
+    this.stack = nestedList.reverse();
+};
+
+
+/**
+ * @this NestedIterator
+ * @returns {boolean}
+ */
+NestedIterator.prototype.hasNext = function() {
+    var next,
+        i;
+    
+    while (this.stack.length > 0) {
+        next = this.stack[this.stack.length - 1];
+        
+        if (next.isInteger()) {
+            return true;
+        }
+        
+        this.stack.pop();
+        
+        for (i = next.getList().length - 1; i >= 0; i--) {
+            this.stack.push(next.getList()[i]);
+        }
+    }
+    
+    return false;
+};
+
+/**
+ * @this NestedIterator
+ * @returns {integer}
+ */
+NestedIterator.prototype.next = function() {
+    return this.stack.pop();
+};
+
+/**
+ * Your NestedIterator will be called like this:
+ * var i = new NestedIterator(nestedList), a = [];
+ * while (i.hasNext()) a.push(i.next());
+*/