{"problem":{"name":"[DTCPC 2024] 小方和小立方","description":{"content":"给你一个由小写字母组成的字符串，求有多少个区间 $[l,r]$，满足这个区间所表示的串是回文的，且每个字符的出现次数不超过 $2$。","description_type":"Markdown"},"platform":"Luogu","limit":{"time_limit":1000,"memory_limit":524288},"difficulty":{"LuoguStyle":"P2"},"is_remote":true,"is_sync":true,"sync_url":null,"sign":"LGP10170"},"statements":[{"statement_type":"Markdown","content":"给你一个由小写字母组成的字符串，求有多少个区间 $[l,r]$，满足这个区间所表示的串是回文的，且每个字符的出现次数不超过 $2$。\n\n## Input\n\n一行一个字符串 $S$（$\\lvert S\\rvert\\leq 5\\times 10^4$）。\n\n## Output\n\n一行一个数，表示答案。\n\n[samples]\n\n## Background\n\n小方不想变成小立方。","is_translate":false,"language":"English"}],"meta":{"iden":"LGP10170","tags":["字符串","2024","洛谷月赛"],"sample_group":[["ababa","8"]],"created_at":"2026-03-03 11:09:25"}}