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2021-03-24 16:51:59 +00:00
parent 4e7045137c
commit 4e184cd95f
1 changed files with 28 additions and 36 deletions
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64
DynamicProgramming/LongestIncreasingSubsequence.java
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@ -17,7 +17,6 @@ public class LongestIncreasingSubsequence {
System.out.println(LIS(arr));
System.out.println(findLISLen(arr));
sc.close();
}
private static int upperBound(int[] ar, int l, int r, int key) {
@ -58,40 +57,33 @@ public class LongestIncreasingSubsequence {
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;
}
/** @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;
}
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;
}
}