leetcode/code/lc341.java at master · mJackie/leetcode · GitHub

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package code;

import java.util.Iterator;

import java.util.List;

import java.util.Stack;

public class lc341 {

public interface NestedInteger {

// @return true if this NestedInteger holds a single integer, rather than a nested list.

public boolean isInteger();

// @return the single integer that this NestedInteger holds, if it holds a single integer

// Return null if this NestedInteger holds a nested list

public Integer getInteger();

// @return the nested list that this NestedInteger holds, if it holds a nested list

// Return null if this NestedInteger holds a single integer

public List<NestedInteger> getList();

}

/**

* Your NestedIterator object will be instantiated and called as such:

* NestedIterator i = new NestedIterator(nestedList);

* while (i.hasNext()) v[f()] = i.next();

public class NestedIterator implements Iterator<Integer> {

Stack<NestedInteger> stack = new Stack<>();

public NestedIterator(List<NestedInteger> nestedList) {

for(int i = nestedList.size() - 1; i >= 0; i--) {

stack.push(nestedList.get(i));

}

@Override

public Integer next() {

return stack.pop().getInteger();

}

@Override

public boolean hasNext() {

while(!stack.isEmpty()) {

NestedInteger curr = stack.peek();

if(curr.isInteger()) {

return true;

}

stack.pop();

for(int i = curr.getList().size() - 1; i >= 0; i--) {

stack.push(curr.getList().get(i));

}

return false;

}

leetcode/code/lc341.java at master · mJackie/leetcode · GitHub

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