Water collected between towers

Question

I recently came across an interview question asked by Amazon and I am not able to find an optimized algorithm to solve this question:

You are given an input array wh

Answer 1

/*** Theta(n) Time COmplexity ***/
        static int trappingRainWater(int ar[],int n)
        {
            int res=0;
            int lmaxArray[]=new int[n];
            int rmaxArray[]=new int[n];
            lmaxArray[0]=ar[0];
            for(int j=1;j=0;j--)
            {
                rmaxArray[j]=Math.max(rmaxArray[j+1], ar[j]);
            }
            for(int i=1;i