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solve speeking iterator #284 in java

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Lines changed: 1 addition & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -231,7 +231,7 @@`
`231`	`231`	`\| 280 \| 🔒 [Wiggle Sort](https://leetcode.com/problems/wiggle-sort) \| \| \|`
`232`	`232`	`\| 281 \| 🔒 [Zigzag Iterator](https://leetcode.com/problems/zigzag-iterator) \| \| \|`
`233`	`233`	`\| 283 \| [Move Zeroes](https://leetcode.com/problems/move-zeroes) \| [![Java](assets/java.png)](src/MoveZeros.java) [![Python](assets/python.png)](python/move_zeroes.py) \| \|`
`234`		`-\| 284 \| [Peeking Iterator](https://leetcode.com/problems/peeking-iterator) \| \| \|`
	`234`	`+\| 284 \| [Peeking Iterator](https://leetcode.com/problems/peeking-iterator) \| [![Java](assets/java.png)](src/PeekingIterator.java) \| \|`
`235`	`235`	`\| 285 \| 🔒 [Inorder Successor in BST](https://leetcode.com/problems/inorder-successor-in-bst) \| \| \|`
`236`	`236`	`\| 286 \| 🔒 [Walls and Gates](https://leetcode.com/problems/walls-and-gates) \| \| \|`
`237`	`237`	`\| 287 \| [Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number) \| \| \|`

Lines changed: 37 additions & 0 deletions

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`@@ -0,0 +1,37 @@`
	`1`	`+// https://leetcode.com/problems/peeking-iterator`
	`2`	`+// T: O(N)`
	`3`	`+// S: O(N)`
	`4`	`+`
	`5`	`+import java.util.Iterator;`
	`6`	`+`
	`7`	`+public class PeekingIterator implements Iterator<Integer> {`
	`8`	`+ final private Iterator<Integer> iterator;`
	`9`	`+ int next;`
	`10`	`+ boolean hasNext;`
	`11`	`+`
	`12`	`+ public PeekingIterator(Iterator<Integer> iterator) {`
	`13`	`+ this.iterator = iterator;`
	`14`	`+ hasNext = iterator.hasNext();`
	`15`	`+ next = iterator.hasNext() ? iterator.next() : 0;`
	`16`	`+ }`
	`17`	`+`
	`18`	`+ // Returns the next element in the iteration without advancing the iterator.`
	`19`	`+ public Integer peek() {`
	`20`	`+ return next;`
	`21`	`+ }`
	`22`	`+`
	`23`	`+ // hasNext() and next() should behave the same as in the Iterator interface.`
	`24`	`+ // Override them if needed.`
	`25`	`+ @Override`
	`26`	`+ public Integer next() {`
	`27`	`+ int result = next;`
	`28`	`+ hasNext = iterator.hasNext();`
	`29`	`+ next = iterator.hasNext() ? iterator.next() : 0;`
	`30`	`+ return result;`
	`31`	`+ }`
	`32`	`+`
	`33`	`+ @Override`
	`34`	`+ public boolean hasNext() {`
	`35`	`+ return hasNext;`
	`36`	`+ }`
	`37`	`+}`

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