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Update LongestIncreasingSubsequence.java

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This commit is contained in:
Alon Firestein
2021-03-24 18:51:20 +02:00
committed by GitHub
parent 8f43cce490
commit 4e7045137c
1 changed files with 41 additions and 3 deletions
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44
DynamicProgramming/LongestIncreasingSubsequence.java
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@ -9,13 +9,15 @@ public class LongestIncreasingSubsequence {
Scanner sc = new Scanner(System.in); Scanner sc = new Scanner(System.in);
int n = sc.nextInt(); int n = sc.nextInt();
int ar[] = new int[n]; int arr[] = new int[n];
for (int i = 0; i < n; i++) { for (int i = 0; i < n; i++) {
ar[i] = sc.nextInt(); arr[i] = sc.nextInt();
} }
System.out.println(LIS(ar)); System.out.println(LIS(arr));
System.out.println(findLISLen(arr));
sc.close(); sc.close();
} }
private static int upperBound(int[] ar, int l, int r, int key) { private static int upperBound(int[] ar, int l, int r, int key) {
@ -56,4 +58,40 @@ public class LongestIncreasingSubsequence {
return length; return length;
} }
/** @author Alon Firestein (https://github.com/alonfirestein) */
// A function for finding the length of the LIS algorithm in O(nlogn) complexity.
public static int findLISLen(int a[]) {
int size = a.length;
int arr[] = new int[size];
arr[0] = a[0];
int lis = 1;
for (int i = 1; i < size; i++) {
int index = binarySearchBetween(arr, lis, a[i]);
arr[index] = a[i];
if (index > lis)
lis++;
}
return lis;
}
// O(logn)
private static int binarySearchBetween(int[] t, int end, int key) {
int left = 0;
int right = end;
if (key < t[0])
return 0;
if (key > t[end])
return end + 1;
while (left < right - 1) {
int middle = (left + right) / 2;
if (t[middle] < key)
left = middle;
else
right = middle;
}
return right;
}
} }