BEST TIME TO BUY AND SELL STOCK WITH COOLDOWN

class Solution {
    public static int ans(int a[],int n,int b,int dp[][]){
        if(n>=a.length) return 0;
        if(dp[n][b]!=-1) return dp[n][b];
        //int p=0,q=0;
        if(b==0){ 
            return dp[n][b]=Math.max(ans(a,n+2,1,dp)+a[n],ans(a,n+1,0,dp));
        }
        else {
            return dp[n][b]=Math.max(ans(a,n+1,0,dp)-a[n],ans(a,n+1,1,dp));
        }
    }
    public int maxProfit(int[] prices) {
        int dp[][]=new int[prices.length][2];
        for(int i=0;i<prices.length;i++){
            for(int j=0;j<2;j++) dp[i][j]=-1;
        }
        return ans(prices,0,1,dp);
    }
}