{"problem":{"name":"[DTCPC 2024] 序列","description":{"content":"定义一个长度为 $n$ 的序列 $\\{p_n\\}$ 的权值 $f(\\{p_n\\})$ 为 $\\max\\limits_{i=1}^n\\{p_i-\\max\\{p_{i-1},p_{i+1}\\}\\}$，特别的，定义 $p_0=p_{n+1}=-\\inf$。 求 $\\sum\\limits_{l=1}^n \\sum\\limits_{r=l+1}^n f(\\{a_l,a_{l+1},\\dots,a_r\\})","description_type":"Markdown"},"platform":"Luogu","limit":{"time_limit":2000,"memory_limit":524288},"difficulty":{"LuoguStyle":"P5"},"is_remote":true,"is_sync":true,"sync_url":null,"sign":"LGP10162"},"statements":[{"statement_type":"Markdown","content":"定义一个长度为 $n$ 的序列 $\\{p_n\\}$ 的权值 $f(\\{p_n\\})$ 为 $\\max\\limits_{i=1}^n\\{p_i-\\max\\{p_{i-1},p_{i+1}\\}\\}$，特别的，定义 $p_0=p_{n+1}=-\\inf$。\n\n求 $\\sum\\limits_{l=1}^n \\sum\\limits_{r=l+1}^n f(\\{a_l,a_{l+1},\\dots,a_r\\})$。\n\n答案对 $2^{32}$ 取模。\n\n## Input\n\n第一行一个正整数 $n$（$1 \\le n \\le 10^6$）。\n\n第二行 $n$ 个整数 $a_i$（$1 \\le a_i \\le 10^9$）。\n\n## Output\n\n一行一个数表示答案。\n\n答案对 $2^{32}$ 取模。\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"LGP10162","tags":["线段树","2024","分治","洛谷月赛","均摊分析"],"sample_group":[["5\n1 3 5 2 3\n","21"],["4\n4 6 3 3","12"]],"created_at":"2026-03-03 11:09:25"}}