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| class NestedIterator { | |
| constructor(nestedList) { | |
| this.stack = []; | |
| this.indexStack = []; | |
| this.nextElement = null; | |
| this.stack.push(nestedList[0]); | |
| this.indexStack.push(0); | |
| } | |
| hasNext() { | |
| while (this.stack.length > 0) { | |
| const list = this.stack[this.stack.length - 1]; | |
| const index = this.indexStack[this.indexStack.length - 1]; | |
| if (index < list.length) { | |
| const nextElement = list[index]; | |
| this.indexStack[this.indexStack.length - 1]++; | |
| if (!isNaN(nextElement) && !Array.isArray(nextElement)) { | |
| // If the next value is an integer, | |
| // store it in 'nextElement' and return true | |
| this.nextElement = nextElement; | |
| return true; | |
| } else { | |
| // If the next value is a nested list, | |
| // push it to the stack for further traversal | |
| this.stack.push(nextElement); | |
| this.indexStack.push(0); | |
| } | |
| } else { | |
| // If the current list is fully traversed, | |
| // pop it from the stack | |
| this.stack.pop(); | |
| this.indexStack.pop(); | |
| } | |
| } | |
| return false; | |
| } | |
| next() { | |
| if (this.hasNext()) { | |
| // If there is a next element, store it in 'val' | |
| // and reset 'nextElement' to null | |
| const val = this.nextElement; | |
| this.nextElement = null; | |
| return val; | |
| } | |
| } | |
| } |
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