剑指 Offer 64. 求1 2 … n

剑指 Offer 64. 求1+2+…+n

class Solution {
    public int sumNums(int n) {
        if (n == 0)
            return 0;
        else if (n == 1)
            return 1;
        return n + sumNums(n - 1);
    }
}