{"trustable":false,"prependHtml":"\u003cstyle type\u003d\"text/css\"\u003e\n section pre {\n display: block;\n padding: 9.5px;\n margin: 0 0 10px;\n font-size: 13px;\n line-height: 1.42857143;\n word-break: break-all;\n word-wrap: break-word;\n color: #333;\n background: rgba(255, 255, 255, 0.5);\n border: 1px solid #ccc;\n border-radius: 6px;\n }\n\u003c/style\u003e\n\u003cscript\u003e\n window.katexOptions \u003d {\n delimiters: [\n {left: \u0027\\\\(\u0027, right: \u0027\\\\)\u0027, display: false},\n {left: \u0027\\\\[\u0027, right: \u0027\\\\]\u0027, display: true}\n ]\n };\n\u003c/script\u003e\n","sections":[{"title":"Problem Statement","value":{"format":"MD","content":"现在有 **N** 个字符串 ***S1,…,SN***,每个字符串的内容要么是 **`AND`**,要么是**`OR`**。\n\n希望你找到,有多少个不同的数组 **X** 满足如下条件:\n\n其中 **X** 数组的长度为 **n + 1**.**(X0 ... Xn)**\n\n**X** 数组中仅有 **`True`** 和 **`False`** 组成。(1 和 0)\n\n通过 X 数组和字符串的“**与逻辑**”,“**或逻辑**”运算,得到长度为 n 的数组 Y,要求 **Yn \u003d `True`**. (Yn \u003d 1)\n\n特殊的 **Y0 \u003d X0**.\n\n**for i \u003e\u003d 1:**\n\n\t**if(S[i] \u003d\u003d \"AND\") Yi \u003d Yi-1 `∧` Xi;**\n\n\t**else if(S[i] \u003d\u003d \"OR\") Yi \u003d Yi-1 `∨` Xi;**"}},{"title":"Constraints","value":{"format":"MD","content":"***1≤N≤60***\n\n***Si is `AND` or `OR`.***"}},{"title":"Input","value":{"format":"MD","content":"数据输入格式如下:\n***N*** \n***S1***\n***.***\n***.***\n***.***\n***SN***\n\n"}},{"title":"Output","value":{"format":"MD","content":"请输出满足条件的 X 数组的数量。"}},{"title":"Sample Input 1","value":{"format":"MD","content":"2\nAND\nOR\n"}},{"title":"Sample Output 1","value":{"format":"MD","content":"5\n\n**例如, 如果 (x0,x1,x2) \u003d (True,False,True), 我们可以得到 y2\u003dTrue, 计算过程如下:**\n\n- **y0 \u003d x0 \u003d True**\n- **y1 \u003d y0 ∧ x1 \u003d True ∧ False \u003d False**\n- **y2 \u003d y1 ∨ x2 \u003d False ∨ True \u003d True**\n\n**所有满足条件的 5 种 X 数组如下:**\n\n- **(True,True,True)**\n- **(True,True,False)**\n- **(True,False,True)**\n- **(False,True,True)**\n- **(False,False,True)**"}},{"title":"Sample Input 2","value":{"format":"MD","content":"5\nOR\nOR\nOR\nOR\nOR"}},{"title":"Sample Output 2","value":{"format":"MD","content":"63\n\n**除了全部都是 `False` 的 X 数组不满足,其他 63 种都满足条件。**"}}]}