LeetCode 1006. Clumsy Factorial

Posted on Edited on In 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
class Solution {
public:
    int clumsy(int N) {
        stack<int> stk;
        stk.push(N--);
        int idx = -1;
        while (N) {
            switch (idx = ++idx % 4) {
            case 0:
                stk.top() *= N--;
                break;
            case 1:
                stk.top() /= N--;
                break;
            case 2:
                stk.push(N--);
                break;
            case 3:
                stk.push(-(N--));
            }
        }
        int sum = 0;
        while (!stk.empty()) {
            sum += stk.top();
            stk.pop();
        }
        return sum;
    }
};