resCount=0; resCount=getNSumCount(n-1,sum-1)+getNSumCount(n-1,sum-2)+ getNSumCount(n-1,sum
sum-1 n=4=2+1 +1, ans=sum-2 n=5=2+1 +2, ans=sum-1 n=6=2+1 + 2+1, ans=sum-2 n=7=2+1 + 2+1 +1, ans=sum