Longest increasing subsequence

class Solution { // Function to find length of longest increasing subsequence. static int longestSubsequence(int n, int a[]) { // tabulation method (bottom up )  int dp[][] = new int[a.length+1][a.length+1]; for(int index = a.length-1;index>=0;index--){ for(int prev = a.length-1;prev>=-1;prev--){ int take = 0; if(prev ==-1 || a[prev] < a[index]){ take = Integer.max(take , 1 + dp[index+1][index+1]); } int dontTake = dp[index+1][prev+1]; dp[index][prev+1] = Integer.max(take,dontTake); } } return dp[0][0]; } //memoization method (top down)  public static int count(int index, int prev, int arr[], int dp[][]){ //base case if(index ==arr.length) return 0; if(dp[index][prev+1]!=-1) return dp[index][prev+1]; int take = 0; if(prev ==-1 || arr[prev] < arr[index]){ take = Integer.max(take , 1 + count(index+1,index,arr,dp)); } int dontTake = count(index+1,prev,arr,dp); return dp[index][prev+1] = Integer.max(take,dontTake); } }