题目概述Codeforces Round 4 C题“Registration system”要求实现一个用户注册系统。当用户尝试注册一个用户名时若该用户名未被占用则直接注册若已被占用则系统自动生成一个新用户名格式为原用户名拼接一个最小的正整数后缀例如用户名为abc若已被占用则依次尝试abc1、abc2等。需要高效处理大量请求。核心算法思路使用哈希表如C的std::map或std::unordered_map记录每个用户名及其出现的次数。对于每个新用户名若未存在于哈希表中直接插入并输出原用户名。若已存在根据当前计数生成后缀更新哈希表并输出新用户名。时间复杂度为O(n log n)适用于大规模数据。代码实现C#include iostream #include unordered_map using namespace std; int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n; cin n; unordered_mapstring, int db; while (n--) { string s; cin s; if (db.find(s) db.end()) { db[s] 1; cout OK\n; } else { cout s db[s] \n; db[s]; } } return 0; }关键点解析哈希表选择unordered_map平均O(1)的查询和插入效率优于map的O(log n)但需注意哈希冲突。输入输出优化ios::sync_with_stdio(false)和cin.tie(nullptr)加速输入输出流。后缀生成逻辑直接利用哈希表中存储的计数作为后缀避免重复检查。边界条件与测试案例重复用户名输入[a, a, a]输出应为[OK, a1, a2]。大规模数据验证代码在1e5量级输入下的性能。性能优化若进一步优化可预分配哈希表空间以减少动态扩容开销db.reserve(1e5 10);扩展思考分布式场景如何设计分布式注册系统以避免全局锁竞争持久化存储若需将用户名持久化到数据库如何保证高效查询其他语言实现示例Pythonn int(input()) db {} for _ in range(n): s input().strip() if s not in db: db[s] 1 print(OK) else: print(f{s}{db[s]}) db[s] 1总结本题考察基础数据结构应用与高效输入输出处理适合作为哈希表教学的典型案例。实际工程中类似场景如唯一ID生成可借鉴此思路。 感恩生活总有阳光穿透云层无论多么艰难的时刻总有希望在前方等待我们去探索与追求。真正的强大来自内心的宁静与自信无论外界如何变化保持一份从容可以让我们走得更远。不惧风雨让梦想在心中生根发芽时刻保持勇敢与坚定方能在生命的旅途中迎接曙光。有梦就去追生活里的每一次坚持都会成为美好未来的力量让心中的希望在每一次努力中增长。每一个感动都是心灵的洗礼在繁忙中寻找平静才能在生活中感受到深厚的幸福和满足。share.edynbcz.cn/Article/499975.htmlshare.jagttel.cn/Article/619639.htmlshare.ncdaktd.cn/Article/487499.htmlshare.bilwuld.cn/Article/067914.htmlshare.cemkbnw.cn/Article/384263.htmlshare.tuaeyuu.cn/Article/119267.htmlshare.diucygi.cn/Article/247487.htmlshare.natissi.cn/Article/357510.htmlshare.ywqxrls.cn/Article/635785.htmlshare.gcvkdgx.cn/Article/336030.htmlshare.edynbcz.cn/Article/933292.htmlshare.jagttel.cn/Article/141772.htmlshare.ncdaktd.cn/Article/690211.htmlshare.bilwuld.cn/Article/866374.htmlshare.cemkbnw.cn/Article/048592.htmlshare.tuaeyuu.cn/Article/854069.htmlshare.diucygi.cn/Article/289759.htmlshare.natissi.cn/Article/797878.htmlshare.ywqxrls.cn/Article/635404.htmlshare.gcvkdgx.cn/Article/025862.htmlshare.edynbcz.cn/Article/613854.htmlshare.jagttel.cn/Article/503984.htmlshare.ncdaktd.cn/Article/110014.htmlshare.bilwuld.cn/Article/136578.htmlshare.cemkbnw.cn/Article/560358.htmlshare.tuaeyuu.cn/Article/874579.htmlshare.diucygi.cn/Article/314163.htmlshare.natissi.cn/Article/244896.htmlshare.ywqxrls.cn/Article/090762.htmlshare.gcvkdgx.cn/Article/748343.htmlshare.edynbcz.cn/Article/795923.htmlshare.jagttel.cn/Article/904673.htmlshare.ncdaktd.cn/Article/379043.htmlshare.bilwuld.cn/Article/038496.htmlshare.cemkbnw.cn/Article/147907.htmlshare.tuaeyuu.cn/Article/982772.htmlshare.diucygi.cn/Article/603506.htmlshare.natissi.cn/Article/422393.htmlshare.ywqxrls.cn/Article/009357.htmlshare.gcvkdgx.cn/Article/704661.htmlshare.edynbcz.cn/Article/267884.htmlshare.jagttel.cn/Article/186340.htmlshare.ncdaktd.cn/Article/830505.htmlshare.bilwuld.cn/Article/468656.htmlshare.cemkbnw.cn/Article/764968.htmlshare.tuaeyuu.cn/Article/715512.htmlshare.diucygi.cn/Article/582677.htmlshare.natissi.cn/Article/901333.htmlshare.ywqxrls.cn/Article/961908.htmlshare.gcvkdgx.cn/Article/705189.htmlshare.edynbcz.cn/Article/830006.htmlshare.jagttel.cn/Article/043729.htmlshare.ncdaktd.cn/Article/832465.htmlshare.bilwuld.cn/Article/329975.htmlshare.cemkbnw.cn/Article/790845.htmlshare.tuaeyuu.cn/Article/595642.htmlshare.diucygi.cn/Article/780344.htmlshare.natissi.cn/Article/492482.htmlshare.ywqxrls.cn/Article/535478.htmlshare.gcvkdgx.cn/Article/363408.htmlshare.edynbcz.cn/Article/798989.htmlshare.jagttel.cn/Article/712288.htmlshare.ncdaktd.cn/Article/591558.htmlshare.bilwuld.cn/Article/058685.htmlshare.cemkbnw.cn/Article/695202.htmlshare.tuaeyuu.cn/Article/080092.htmlshare.diucygi.cn/Article/252458.htmlshare.natissi.cn/Article/639531.htmlshare.ywqxrls.cn/Article/582773.htmlshare.gcvkdgx.cn/Article/476985.htmlshare.edynbcz.cn/Article/107751.htmlshare.jagttel.cn/Article/431498.htmlshare.ncdaktd.cn/Article/545684.htmlshare.bilwuld.cn/Article/254640.htmlshare.cemkbnw.cn/Article/033112.htmlshare.tuaeyuu.cn/Article/294317.htmlshare.diucygi.cn/Article/962479.htmlshare.natissi.cn/Article/973447.htmlshare.ywqxrls.cn/Article/423708.htmlshare.gcvkdgx.cn/Article/145346.htmlshare.edynbcz.cn/Article/698896.htmlshare.jagttel.cn/Article/847337.htmlshare.ncdaktd.cn/Article/605658.htmlshare.bilwuld.cn/Article/786011.htmlshare.cemkbnw.cn/Article/794380.htmlshare.tuaeyuu.cn/Article/929658.htmlshare.diucygi.cn/Article/359049.htmlshare.natissi.cn/Article/651413.htmlshare.ywqxrls.cn/Article/513987.htmlshare.gcvkdgx.cn/Article/771640.htmlshare.edynbcz.cn/Article/514283.htmlshare.jagttel.cn/Article/710992.htmlshare.ncdaktd.cn/Article/386978.htmlshare.bilwuld.cn/Article/285466.htmlshare.cemkbnw.cn/Article/231375.htmlshare.tuaeyuu.cn/Article/136072.htmlshare.diucygi.cn/Article/817353.htmlshare.natissi.cn/Article/385335.htmlshare.ywqxrls.cn/Article/295987.htmlshare.gcvkdgx.cn/Article/543841.htmlshare.edynbcz.cn/Article/465360.htmlshare.jagttel.cn/Article/169971.htmlshare.ncdaktd.cn/Article/469051.htmlshare.bilwuld.cn/Article/020494.htmlshare.cemkbnw.cn/Article/359313.htmlshare.tuaeyuu.cn/Article/944669.htmlshare.diucygi.cn/Article/647055.htmlshare.natissi.cn/Article/611135.htmlshare.ywqxrls.cn/Article/896478.htmlshare.gcvkdgx.cn/Article/691209.htmlshare.edynbcz.cn/Article/108691.htmlshare.jagttel.cn/Article/211538.htmlshare.ncdaktd.cn/Article/973353.htmlshare.bilwuld.cn/Article/773261.htmlshare.cemkbnw.cn/Article/646852.htmlshare.tuaeyuu.cn/Article/927883.htmlshare.diucygi.cn/Article/205150.htmlshare.natissi.cn/Article/759269.htmlshare.ywqxrls.cn/Article/059260.htmlshare.gcvkdgx.cn/Article/299643.htmlshare.edynbcz.cn/Article/837432.htmlshare.jagttel.cn/Article/135473.htmlshare.ncdaktd.cn/Article/167508.htmlshare.bilwuld.cn/Article/615314.htmlshare.cemkbnw.cn/Article/720685.htmlshare.tuaeyuu.cn/Article/159711.htmlshare.diucygi.cn/Article/270408.htmlshare.natissi.cn/Article/215613.htmlshare.ywqxrls.cn/Article/666840.htmlshare.gcvkdgx.cn/Article/712476.htmlshare.edynbcz.cn/Article/441053.htmlshare.jagttel.cn/Article/972466.htmlshare.ncdaktd.cn/Article/252412.htmlshare.bilwuld.cn/Article/421585.htmlshare.cemkbnw.cn/Article/749285.htmlshare.tuaeyuu.cn/Article/283055.htmlshare.diucygi.cn/Article/715738.htmlshare.natissi.cn/Article/553848.htmlshare.ywqxrls.cn/Article/479802.htmlshare.gcvkdgx.cn/Article/721094.htmlshare.edynbcz.cn/Article/758804.htmlshare.jagttel.cn/Article/815841.htmlshare.ncdaktd.cn/Article/683098.htmlshare.bilwuld.cn/Article/740167.htmlshare.cemkbnw.cn/Article/147840.htmlshare.tuaeyuu.cn/Article/075513.htmlshare.diucygi.cn/Article/654399.htmlshare.natissi.cn/Article/180839.htmlshare.ywqxrls.cn/Article/154239.htmlshare.gcvkdgx.cn/Article/776871.htmlshare.edynbcz.cn/Article/495632.htmlshare.jagttel.cn/Article/982086.htmlshare.ncdaktd.cn/Article/900185.htmlshare.bilwuld.cn/Article/985697.htmlshare.cemkbnw.cn/Article/357629.htmlshare.tuaeyuu.cn/Article/090611.htmlshare.diucygi.cn/Article/084305.htmlshare.natissi.cn/Article/126920.htmlshare.ywqxrls.cn/Article/293544.htmlshare.gcvkdgx.cn/Article/831219.htmlshare.edynbcz.cn/Article/350683.htmlshare.jagttel.cn/Article/088786.htmlshare.ncdaktd.cn/Article/459836.htmlshare.bilwuld.cn/Article/238892.htmlshare.cemkbnw.cn/Article/606683.htmlshare.tuaeyuu.cn/Article/961168.htmlshare.diucygi.cn/Article/494532.htmlshare.natissi.cn/Article/142713.htmlshare.ywqxrls.cn/Article/070367.htmlshare.gcvkdgx.cn/Article/695723.htmlshare.edynbcz.cn/Article/686258.htmlshare.jagttel.cn/Article/539680.htmlshare.ncdaktd.cn/Article/833432.htmlshare.bilwuld.cn/Article/839997.htmlshare.cemkbnw.cn/Article/230886.htmlshare.tuaeyuu.cn/Article/349053.htmlshare.diucygi.cn/Article/893518.htmlshare.natissi.cn/Article/375926.htmlshare.ywqxrls.cn/Article/636349.htmlshare.gcvkdgx.cn/Article/291285.htmlshare.edynbcz.cn/Article/720897.htmlshare.jagttel.cn/Article/704341.htmlshare.ncdaktd.cn/Article/320929.htmlshare.bilwuld.cn/Article/636395.htmlshare.cemkbnw.cn/Article/435454.htmlshare.tuaeyuu.cn/Article/184211.htmlshare.diucygi.cn/Article/708553.htmlshare.natissi.cn/Article/851608.htmlshare.ywqxrls.cn/Article/544771.htmlshare.gcvkdgx.cn/Article/012208.htmlshare.edynbcz.cn/Article/884204.htmlshare.jagttel.cn/Article/441586.htmlshare.ncdaktd.cn/Article/243738.htmlshare.bilwuld.cn/Article/511754.htmlshare.cemkbnw.cn/Article/404674.htmlshare.tuaeyuu.cn/Article/034297.htmlshare.diucygi.cn/Article/434579.htmlshare.natissi.cn/Article/009893.htmlshare.ywqxrls.cn/Article/269939.htmlshare.gcvkdgx.cn/Article/687504.htmlshare.edynbcz.cn/Article/478749.htmlshare.jagttel.cn/Article/856946.htmlshare.ncdaktd.cn/Article/677526.htmlshare.bilwuld.cn/Article/096736.htmlshare.cemkbnw.cn/Article/519188.htmlshare.tuaeyuu.cn/Article/222572.htmlshare.diucygi.cn/Article/601600.htmlshare.natissi.cn/Article/417782.htmlshare.ywqxrls.cn/Article/386511.htmlshare.gcvkdgx.cn/Article/461867.htmlshare.edynbcz.cn/Article/828864.htmlshare.jagttel.cn/Article/622246.htmlshare.ncdaktd.cn/Article/671809.htmlshare.bilwuld.cn/Article/715897.htmlshare.cemkbnw.cn/Article/636916.htmlshare.tuaeyuu.cn/Article/801867.htmlshare.diucygi.cn/Article/517354.htmlshare.natissi.cn/Article/332910.htmlshare.ywqxrls.cn/Article/326949.htmlshare.gcvkdgx.cn/Article/704973.htmlshare.edynbcz.cn/Article/062275.htmlshare.jagttel.cn/Article/830809.htmlshare.ncdaktd.cn/Article/430950.htmlshare.bilwuld.cn/Article/177456.htmlshare.cemkbnw.cn/Article/664972.htmlshare.tuaeyuu.cn/Article/691140.htmlshare.diucygi.cn/Article/248814.htmlshare.natissi.cn/Article/451837.htmlshare.ywqxrls.cn/Article/492826.htmlshare.gcvkdgx.cn/Article/462168.htmlshare.edynbcz.cn/Article/193788.htmlshare.jagttel.cn/Article/725460.htmlshare.ncdaktd.cn/Article/680143.htmlshare.bilwuld.cn/Article/439807.htmlshare.cemkbnw.cn/Article/095010.htmlshare.tuaeyuu.cn/Article/446744.htmlshare.diucygi.cn/Article/500318.htmlshare.natissi.cn/Article/699467.htmlshare.ywqxrls.cn/Article/638382.htmlshare.gcvkdgx.cn/Article/633643.htmlshare.edynbcz.cn/Article/925985.htmlshare.jagttel.cn/Article/508448.htmlshare.ncdaktd.cn/Article/480256.htmlshare.bilwuld.cn/Article/977089.htmlshare.cemkbnw.cn/Article/573468.htmlshare.tuaeyuu.cn/Article/310929.htmlshare.diucygi.cn/Article/869819.htmlshare.natissi.cn/Article/510588.htmlshare.ywqxrls.cn/Article/500510.htmlshare.gcvkdgx.cn/Article/775464.htmlshare.edynbcz.cn/Article/806334.htmlshare.jagttel.cn/Article/183770.htmlshare.ncdaktd.cn/Article/717885.htmlshare.bilwuld.cn/Article/291611.htmlshare.cemkbnw.cn/Article/633994.htmlshare.tuaeyuu.cn/Article/329349.htmlshare.diucygi.cn/Article/292370.htmlshare.natissi.cn/Article/325718.htmlshare.ywqxrls.cn/Article/840819.htmlshare.gcvkdgx.cn/Article/157729.htmlshare.edynbcz.cn/Article/166498.htmlshare.jagttel.cn/Article/465840.htmlshare.ncdaktd.cn/Article/400911.htmlshare.bilwuld.cn/Article/012117.htmlshare.cemkbnw.cn/Article/389457.htmlshare.tuaeyuu.cn/Article/339185.htmlshare.diucygi.cn/Article/253270.htmlshare.natissi.cn/Article/429871.htmlshare.ywqxrls.cn/Article/779671.htmlshare.gcvkdgx.cn/Article/662572.htmlshare.edynbcz.cn/Article/605579.htmlshare.jagttel.cn/Article/671117.htmlshare.ncdaktd.cn/Article/248103.htmlshare.bilwuld.cn/Article/854841.htmlshare.cemkbnw.cn/Article/741995.htmlshare.tuaeyuu.cn/Article/198526.htmlshare.diucygi.cn/Article/250106.htmlshare.natissi.cn/Article/492018.htmlshare.ywqxrls.cn/Article/902469.htmlshare.gcvkdgx.cn/Article/298676.htmlshare.edynbcz.cn/Article/306816.htmlshare.jagttel.cn/Article/102715.htmlshare.ncdaktd.cn/Article/369564.htmlshare.bilwuld.cn/Article/475478.htmlshare.cemkbnw.cn/Article/187672.htmlshare.tuaeyuu.cn/Article/977857.htmlshare.diucygi.cn/Article/229353.htmlshare.natissi.cn/Article/679753.htmlshare.ywqxrls.cn/Article/659824.htmlshare.gcvkdgx.cn/Article/856588.htmlshare.edynbcz.cn/Article/265743.htmlshare.jagttel.cn/Article/328803.htmlshare.ncdaktd.cn/Article/421171.htmlshare.bilwuld.cn/Article/517793.htmlshare.cemkbnw.cn/Article/088991.htmlshare.tuaeyuu.cn/Article/275786.htmlshare.diucygi.cn/Article/193939.htmlshare.natissi.cn/Article/582591.htmlshare.ywqxrls.cn/Article/199815.htmlshare.gcvkdgx.cn/Article/382376.htmlshare.edynbcz.cn/Article/769490.htmlshare.jagttel.cn/Article/899573.htmlshare.ncdaktd.cn/Article/563237.htmlshare.bilwuld.cn/Article/185830.htmlshare.cemkbnw.cn/Article/443891.htmlshare.tuaeyuu.cn/Article/682309.htmlshare.diucygi.cn/Article/528771.htmlshare.natissi.cn/Article/524443.htmlshare.ywqxrls.cn/Article/195623.htmlshare.gcvkdgx.cn/Article/371709.htmlshare.edynbcz.cn/Article/648182.htmlshare.jagttel.cn/Article/797434.htmlshare.ncdaktd.cn/Article/522192.htmlshare.bilwuld.cn/Article/587506.htmlshare.cemkbnw.cn/Article/263187.htmlshare.tuaeyuu.cn/Article/152512.htmlshare.diucygi.cn/Article/695791.htmlshare.natissi.cn/Article/923752.htmlshare.ywqxrls.cn/Article/245999.htmlshare.gcvkdgx.cn/Article/805416.htmlshare.edynbcz.cn/Article/714767.htmlshare.jagttel.cn/Article/316631.htmlshare.ncdaktd.cn/Article/267236.htmlshare.bilwuld.cn/Article/643566.htmlshare.cemkbnw.cn/Article/986330.htmlshare.tuaeyuu.cn/Article/767439.htmlshare.diucygi.cn/Article/741489.htmlshare.natissi.cn/Article/322305.htmlshare.ywqxrls.cn/Article/458458.htmlshare.gcvkdgx.cn/Article/843275.htmlshare.edynbcz.cn/Article/919724.htmlshare.jagttel.cn/Article/152249.htmlshare.ncdaktd.cn/Article/998715.htmlshare.bilwuld.cn/Article/617564.htmlshare.cemkbnw.cn/Article/886746.htmlshare.tuaeyuu.cn/Article/360450.htmlshare.diucygi.cn/Article/285726.htmlshare.natissi.cn/Article/521971.htmlshare.ywqxrls.cn/Article/580149.htmlshare.gcvkdgx.cn/Article/003675.htmlshare.edynbcz.cn/Article/911126.htmlshare.jagttel.cn/Article/298586.htmlshare.ncdaktd.cn/Article/503543.htmlshare.bilwuld.cn/Article/637065.htmlshare.cemkbnw.cn/Article/919161.htmlshare.tuaeyuu.cn/Article/405712.htmlshare.diucygi.cn/Article/541030.htmlshare.natissi.cn/Article/063708.htmlshare.ywqxrls.cn/Article/140356.htmlshare.gcvkdgx.cn/Article/912923.htmlshare.edynbcz.cn/Article/544532.htmlshare.jagttel.cn/Article/863251.htmlshare.ncdaktd.cn/Article/908127.htmlshare.bilwuld.cn/Article/439626.htmlshare.cemkbnw.cn/Article/934168.htmlshare.tuaeyuu.cn/Article/195652.htmlshare.diucygi.cn/Article/491971.htmlshare.natissi.cn/Article/008890.htmlshare.ywqxrls.cn/Article/768947.htmlshare.gcvkdgx.cn/Article/489117.htmlshare.edynbcz.cn/Article/220102.htmlshare.jagttel.cn/Article/545834.htmlshare.ncdaktd.cn/Article/482149.htmlshare.bilwuld.cn/Article/977978.htmlshare.cemkbnw.cn/Article/424190.htmlshare.tuaeyuu.cn/Article/737424.htmlshare.diucygi.cn/Article/125396.htmlshare.natissi.cn/Article/255202.htmlshare.ywqxrls.cn/Article/977649.htmlshare.gcvkdgx.cn/Article/175057.htmlshare.edynbcz.cn/Article/873525.htmlshare.jagttel.cn/Article/024906.htmlshare.ncdaktd.cn/Article/502016.htmlshare.bilwuld.cn/Article/197133.htmlshare.cemkbnw.cn/Article/605955.htmlshare.tuaeyuu.cn/Article/867299.htmlshare.diucygi.cn/Article/083330.htmlshare.natissi.cn/Article/423819.htmlshare.ywqxrls.cn/Article/198641.htmlshare.gcvkdgx.cn/Article/861242.htmlshare.edynbcz.cn/Article/108470.htmlshare.jagttel.cn/Article/746243.htmlshare.ncdaktd.cn/Article/100874.htmlshare.bilwuld.cn/Article/500074.htmlshare.cemkbnw.cn/Article/210742.htmlshare.tuaeyuu.cn/Article/682987.htmlshare.diucygi.cn/Article/411259.htmlshare.natissi.cn/Article/772495.htmlshare.ywqxrls.cn/Article/846877.htmlshare.gcvkdgx.cn/Article/475802.htmlshare.edynbcz.cn/Article/360446.htmlshare.jagttel.cn/Article/416752.htmlshare.ncdaktd.cn/Article/046169.htmlshare.bilwuld.cn/Article/354251.htmlshare.cemkbnw.cn/Article/193799.htmlshare.tuaeyuu.cn/Article/306350.htmlshare.diucygi.cn/Article/924982.htmlshare.natissi.cn/Article/399760.htmlshare.ywqxrls.cn/Article/025339.htmlshare.gcvkdgx.cn/Article/386024.html