Trapping Rain Water.java

public class Solution {
    public int trap(int[] A) {
        // Start typing your Java solution below
        // DO NOT write main() function
      int length=A.length;
      if(length==0|| length==1) return 0; 
      int [] leftMost=new int [length]; int tempL=A[0];
      int [] rightMost=new int[length]; int tempR=A[length-1];
      int sum=0; 
      //first pass which stores the right most value
      for(int j=length-1; j>=0; j--)
      {
          if(tempR<A[j])
          {
              tempR=A[j];
          }
          rightMost[j]=tempR;
      }
      //second pass which calculates the right most value and adds the total values
      for(int i=1; i<length; i++)
      {
          if(tempL<A[i])
          {
              tempL=A[i]; 
          }
          leftMost[i]=tempL; 
          sum+=(A[i]==leftMost[i] || A[i]==rightMost[i] )? 0: Math.min(leftMost[i], rightMost[i])-A[i];
      }
      return sum; 
}
}