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Commit 869bc30

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flatten nestlist + minor refactorings: done
1 parent b449afd commit 869bc30

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4 files changed

+117
-38
lines changed

4 files changed

+117
-38
lines changed
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package com.leetcode.recursion;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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/**
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* Level: Medium
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* Link: https://leetcode.com/problems/flatten-nested-list-iterator/
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* Description:
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* Given a nested list of integers, implement an iterator to flatten it.
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*
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* Each element is either an integer, or a list -- whose elements may also be integers or other lists.
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*
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* Example 1:
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* Input: [[1,1],2,[1,1]]
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* Output: [1,1,2,1,1]
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* Explanation: By calling next repeatedly until hasNext returns false,
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* the order of elements returned by next should be: [1,1,2,1,1].
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*
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* Example 2:
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* Input: [1,[4,[6]]]
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* Output: [1,4,6]
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* Explanation: By calling next repeatedly until hasNext returns false,
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* the order of elements returned by next should be: [1,4,6].
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*
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* Runtime: <a href="https://leetcode.com/submissions/detail/250996020/">2 ms</a>.
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*
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* @author rampatra
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* @since 2019年08月12日
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*/
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public class FlattenNestListIterator implements Iterator<Integer> {
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private int index;
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private List<Integer> flattenedList;
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public FlattenNestListIterator(List<NestedInteger> nestedList) {
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index = 0;
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flattenedList = getFlattenedList(nestedList);
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}
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private List<Integer> getFlattenedList(List<NestedInteger> nestedList) {
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List<Integer> flattenedList = new ArrayList<>();
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for (NestedInteger nestedInteger : nestedList) {
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if (nestedInteger.isInteger()) {
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flattenedList.add(nestedInteger.getInteger());
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} else {
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flattenedList.addAll(getFlattenedList(nestedInteger.getList()));
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}
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}
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return flattenedList;
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}
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@Override
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public Integer next() {
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return flattenedList.get(index++);
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}
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@Override
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public boolean hasNext() {
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return index < flattenedList.size();
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}
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public static void main(String[] args) {
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// TODO add some test cases
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}
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}
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package com.leetcode.recursion;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* Class needed for various problems like {@link NestedListWeightSumII}, {@link FlattenNestListIterator}, etc.
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*
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* @author rampatra
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* @since 2019年08月12日
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*/
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public class NestedInteger {
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private Integer integer;
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private List<NestedInteger> list;
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public NestedInteger() {
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this.list = new ArrayList<>();
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}
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public NestedInteger(int integer) {
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this.integer = integer;
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this.list = new ArrayList<>();
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}
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public boolean isInteger() {
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return this.integer != null;
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}
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public Integer getInteger() {
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return integer;
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}
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public void setInteger(Integer integer) {
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this.integer = integer;
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}
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public List<NestedInteger> getList() {
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return list;
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}
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public NestedInteger add(NestedInteger nestedInteger) {
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this.list.add(nestedInteger);
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return this;
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}
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}

‎src/main/java/com/leetcode/arrays/NestedListWeightSum.java renamed to ‎src/main/java/com/leetcode/recursion/NestedListWeightSum.java

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package com.leetcode.arrays;
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package com.leetcode.recursion;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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‎src/main/java/com/leetcode/arrays/NestedListWeightSumII.java renamed to ‎src/main/java/com/leetcode/recursion/NestedListWeightSumII.java

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package com.leetcode.arrays;
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package com.leetcode.recursion;
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import java.util.*;
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@@ -77,40 +77,4 @@ public static void main(String[] args) {
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assertEquals(17, nestedSum(Collections.singletonList(ni)));
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}
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}
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class NestedInteger {
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private Integer integer;
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private List<NestedInteger> list;
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public NestedInteger() {
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this.list = new ArrayList<>();
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}
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public NestedInteger(int integer) {
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this.integer = integer;
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this.list = new ArrayList<>();
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}
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public boolean isInteger() {
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return this.integer != null;
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}
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public Integer getInteger() {
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return integer;
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}
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public void setInteger(Integer integer) {
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this.integer = integer;
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}
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public List<NestedInteger> getList() {
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return list;
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}
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public NestedInteger add(NestedInteger nestedInteger) {
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this.list.add(nestedInteger);
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return this;
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}
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}

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