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Create Find Duplicate in Array .java

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	`1`	`+/*`
	`2`	`+Given a read only array of n + 1 integers between 1 and n, find one number that repeats in linear time using less than O(n) space and traversing the stream sequentially O(1) times.`
	`3`	`+`
	`4`	`+Sample Input:`
	`5`	`+`
	`6`	`+[3 4 1 4 1]`
	`7`	`+Sample Output:`
	`8`	`+`
	`9`	`+1`
	`10`	`+If there are multiple possible answers ( like in the sample case above ), output any one.`
	`11`	`+`
	`12`	`+If there is no duplicate, output -1`
	`13`	`+*/`
	`14`	`+`
	`15`	`+public class Solution {`
	`16`	`+ // DO NOT MODIFY THE LIST. IT IS READ ONLY`
	`17`	`+ public int repeatedNumber(final List<Integer> A) {`
	`18`	`+ int len = A.size();`
	`19`	`+ if(len == 0)`
	`20`	`+ return -1;`
	`21`	`+ int slow = A.get(0);`
	`22`	`+ int fast = A.get(A.get(0));`
	`23`	`+ while (slow != fast) {`
	`24`	`+ slow = A.get(slow);`
	`25`	`+ fast = A.get(A.get(fast));`
	`26`	`+ }`
	`27`	`+`
	`28`	`+ fast = 0;`
	`29`	`+ while (slow != fast) {`
	`30`	`+ slow = A.get(slow);`
	`31`	`+ fast = A.get(fast);`
	`32`	`+ }`
	`33`	`+ if(slow==0) return -1;`
	`34`	`+ return slow;`
	`35`	`+ }`
	`36`	`+}`

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