{"trustable":true,"sections":[{"title":"","value":{"format":"HTML","content":"\u003cstyle type\u003d\"text/css\"\u003e .sampledata { font-family: \"Courier New\", Courier, monospace; white-space: pre; }\u003c/style\u003e\u003cp\u003e 有n个木块排成一行,从左到右依次编号为1~n。你有k种颜色的油漆,其中第i种颜色的油漆足够涂ci个木块。\u003cbr\u003e 所有油漆刚好足够涂满所有木块,即c1+c2+...+ck\u003dn。相邻两个木块涂相同色显得很难看,所以你希望统计任意两\u003cbr\u003e 个相邻木块颜色不同的着色方案。\u003c/p\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cp\u003e 第一行为一个正整数k,第二行包含k个整数c1, c2, ... , ck。\u003c/p\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003e 输出一个整数,即方案总数模1,000,000,007的结果。\u003c/p\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cspan class\u003dsampledata\u003e3\r\n1 2 3\u003c/span\u003e\u003c/div\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cspan class\u003dsampledata\u003e10\u003c/span\u003e\u003c/div\u003e"}},{"title":"Hint","value":{"format":"HTML","content":"\u003cp\u003e\u003c/p\u003e\n\u003cp\u003e\u003cspan style\u003d\"font-size: medium\"\u003e\u0026nbsp;100%的数据满足:1 \u0026lt;\u003d k \u0026lt;\u003d 15, 1 \u0026lt;\u003d ci \u0026lt;\u003d 5\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e"}}]}