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LongestIncreasingSubsequence.java
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65 lines (50 loc) · 1.67 KB
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package DynamicProgramming;
import java.util.Scanner;
/**
* @author Afrizal Fikri (https://github.com/icalF)
*/
public class LongestIncreasingSubsequence {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int ar[] = new int[n];
for (int i = 0; i < n; i++) {
ar[i] = sc.nextInt();
}
System.out.println(LIS(ar));
sc.close();
}
private static int upperBound(int[] ar, int l, int r, int key) {
while (l < r - 1) {
int m = (l + r) / 2;
if (ar[m] >= key)
r = m;
else
l = m;
}
return r;
}
private static int LIS(int[] array) {
int N = array.length;
if (N == 0)
return 0;
int[] tail = new int[N];
// always points empty slot in tail
int length = 1;
tail[0] = array[0];
for (int i = 1; i < N; i++) {
// new smallest value
if (array[i] < tail[0])
tail[0] = array[i];
// array[i] extends largest subsequence
else if (array[i] > tail[length - 1])
tail[length++] = array[i];
// array[i] will become end candidate of an existing subsequence or
// Throw away larger elements in all LIS, to make room for upcoming grater elements than array[i]
// (and also, array[i] would have already appeared in one of LIS, identify the location and replace it)
else
tail[upperBound(tail, -1, length - 1, array[i])] = array[i];
}
return length;
}
}