栈

难度中等

题目描述

解题思路

遇到乘除立即算，遇到加减先入栈
https://leetcode-cn.com/problems/clumsy-factorial/solution/fu-xue-ming-zhu-yu-dao-cheng-chu-li-ji-s-furg/

Code

public int clumsy(int N) {
    Stack<Integer> stack = new Stack<>();
    int op = 0;
    int sum = 0;
    stack.push(N);
    for (int i = N - 1; i > 0; i--) {
        if (op == 0) {
            stack.push(stack.pop() * i);
        } else if (op == 1) {
            stack.push(stack.pop() / i);
        } else if (op == 2) {
            stack.push(i);
        } else {
            stack.push(-i);
        }
        op = (op + 1) % 4;
    }
    while (!stack.isEmpty()) {
        sum += stack.pop();
    }
    return sum;
}