{"id":7383,"date":"2026-07-21T00:47:40","date_gmt":"2026-07-20T16:47:40","guid":{"rendered":"https:\/\/i007.cc\/wordpress\/?p=7383"},"modified":"2026-07-21T01:06:37","modified_gmt":"2026-07-20T17:06:37","slug":"%e6%9c%80%e5%b0%8f%e8%a6%86%e7%9b%96%e5%ad%90%e4%b8%b2%ef%bc%88minimum-window-substring%ef%bc%89","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/7383","title":{"rendered":"\u6700\u5c0f\u8986\u76d6\u5b50\u4e32\uff08Minimum Window Substring\uff09"},"content":{"rendered":"

\u529b\u6263\u7b2c 76 \u9898\u3002\u7ed9\u5b9a\u5b57\u7b26\u4e32 s<\/code> \u548c t<\/code>\uff0c\u627e s<\/code> \u4e2d\u5305\u542b t<\/code> \u6240\u6709\u5b57\u7b26\u7684\u6700\u77ed\u5b50\u4e32<\/strong>\u3002<\/p>\n

\n

\u6838\u5fc3\u601d\u8def\uff1a\u6ed1\u52a8\u7a97\u53e3 + \u8ba1\u6570\u5668<\/h4>\n

\u8fd8\u662f\u6ed1\u52a8\u7a97\u53e3\uff0c\u4f46\u6bd4\u4e0a\u9898\u591a\u4e00\u4e2a\u96be\u70b9\u2014\u2014\u9700\u8981\u77e5\u9053\u7a97\u53e3\u662f\u5426\u5df2\u7ecf”\u8986\u76d6”\u4e86 t<\/code> \u7684\u6240\u6709\u5b57\u7b26\u3002<\/p>\n

\u5173\u952e\u5728\u4e8e\u8bbe\u8ba1\u4e00\u4e2a need<\/code> \u53d8\u91cf<\/strong>\u6765\u8ffd\u8e2a”\u8fd8\u7f3a\u51e0\u79cd\u5b57\u7b26”\uff0c\u907f\u514d\u6bcf\u6b21\u90fd\u904d\u5386\u6574\u4e2a\u54c8\u5e0c\u8868\u6765\u5224\u65ad\u662f\u5426\u6ee1\u8db3\u6761\u4ef6\u3002<\/p>\n

\n

\u6700\u4f18\u89e3\u6cd5\uff1aO(n) \u6ed1\u52a8\u7a97\u53e3<\/h4>\n
\n
class Solution {\r\npublic:\r\n    string minWindow(string s, string t) {\r\n        int freq[128] = {}; \/\/ \u8bb0\u5f55 t \u4e2d\u5404\u5b57\u7b26\u8fd8\u9700\u8981\u591a\u5c11\u4e2a\r\n        for (char c : t)\r\n            freq[c]++;\r\n\r\n        int need = t.size(); \/\/ \u8fd8\u9700\u8981\u51d1\u9f50\u591a\u5c11\u4e2a\u5b57\u7b26\uff08\u542b\u91cd\u590d\uff09\r\n        int left = 0;\r\n        int ans_start = 0, ans_len = INT_MAX;\r\n\r\n        for (int right = 0; right < s.size(); right++) {\r\n            \/\/ 1. \u53f3\u8fb9\u5b57\u7b26\u5165\u7a97\u53e3\r\n            char rc = s[right];\r\n            if (freq[rc] > 0)\r\n                need--; \/\/ \u8fd9\u4e2a\u5b57\u7b26\u662f t \u8fd8\u7f3a\u7684\uff0cneed--\r\n            freq[rc]--;\r\n\r\n            \/\/ 2. \u7a97\u53e3\u5df2\u8986\u76d6 t\uff0c\u5c1d\u8bd5\u6536\u7f29\u5de6\u8fb9\r\n            while (need == 0) {\r\n                \/\/ \u66f4\u65b0\u6700\u4f18\u89e3\r\n                if (right - left + 1 < ans_len) {\r\n                    ans_len = right - left + 1;\r\n                    ans_start = left;\r\n                }\r\n                \/\/ \u5de6\u8fb9\u5b57\u7b26\u51fa\u7a97\u53e3\r\n                char lc = s[left];\r\n                freq[lc]++;\r\n                if (freq[lc] > 0)\r\n                    need++; \/\/ \u8fd9\u4e2a\u5b57\u7b26\u91cd\u65b0\u53d8\u6210\u7f3a\u7684\uff0cneed++\r\n                left++;\r\n            }\r\n        }\r\n\r\n        return ans_len == INT_MAX ? \"\" : s.substr(ans_start, ans_len);\r\n    }\r\n};<\/pre>\n
 <\/p>\n<\/div>\n
<\/div>\n
\n
\u7406\u89e3\u4e24\u4e2a\u5173\u952e\u8bbe\u8ba1<\/h4>\n
\u2460 freq<\/code> \u6570\u7ec4\u7684\u542b\u4e49\u968f\u7740\u7a97\u53e3\u53d8\u5316<\/strong><\/p>\n
\u521d\u59cb\u65f6 freq[c]<\/code> \u662f t \u4e2d c \u7684\u9700\u6c42\u91cf\u3002\u7a97\u53e3\u53f3\u6269\u65f6 freq[rc]--<\/code>\uff0c\u5de6\u7f29\u65f6 freq[lc]++<\/code>\u3002\u6240\u4ee5\u5b83\u59cb\u7ec8\u4ee3\u8868\u5f53\u524d\u7a97\u53e3\u76f8\u5bf9\u4e8e t \u7684\u51c0\u7f3a\u53e3<\/strong>\uff1a<\/p>\n
    \n
  • freq[c] > 0<\/code>\uff1a\u7a97\u53e3\u8fd8\u6b20 t \u4e2d c \u7684\u5b57\u7b26<\/li>\n
  • freq[c] <= 0<\/code>\uff1a\u7a97\u53e3\u4e2d c \u5df2\u7ecf\u591f\u4e86\uff08\u751a\u81f3\u591a\u4f59\uff09<\/li>\n<\/ul>\n
    \u2461 need<\/code> \u662f\u7cbe\u9ad3<\/strong><\/p>\n
    need<\/code> \u8bb0\u5f55\u7684\u662f”\u8fd8\u6709\u51e0\u4e2a\u5b57\u7b26\u4f4d\u7f6e\u672a\u88ab\u6ee1\u8db3”\u3002\u53ea\u6709\u5f53 freq[c]<\/code> \u4ece 1 \u53d8\u5230 0\uff08\u6b63\u597d\u8865\u4e0a\u7f3a\u53e3\uff09\u65f6\uff0cneed--<\/code> \u624d\u6709\u610f\u4e49\uff1b\u4ece 0 \u53d8\u5230 -1 \u662f\u591a\u4f59\u7684\u5b57\u7b26\uff0c\u4e0d\u6539\u53d8 need<\/code>\u3002\u8fd9\u6837 need == 0<\/code> \u5c31\u7cbe\u786e\u7b49\u4ef7\u4e8e”\u7a97\u53e3\u5df2\u5b8c\u5168\u8986\u76d6 t”\uff0c\u5224\u65ad O(1) \u5b8c\u6210\u3002<\/p>\n
    \n
    \u5b8c\u6574\u8d70\u4e00\u904d\u4f8b\u5b50<\/h4>\n
    \n
    \n
    <\/div>\n<\/div>\n
    \n
    s = \"ADOBECODEBANC\", t = \"ABC\"\r\n\u521d\u59cb: freq = {A:1, B:1, C:1}, need = 3\r\n\r\nright \u6269\u5f20\u76f4\u5230 need == 0\uff08\u627e\u5230\u7b2c\u4e00\u4e2a\u8986\u76d6\u7a97\u53e3 \"ADOBEC\"\uff09\r\n\u2192 \u5f00\u59cb\u6536\u7f29 left\uff0c\u66f4\u65b0\u6700\u4f18\u89e3\r\n\u2192 left \u79fb\u5230 'D' \u65f6\uff0cA \u4ece\u7a97\u53e3\u79fb\u51fa\uff0cneed \u53d8\u56de 1\r\n\u2192 right \u7ee7\u7eed\u6269\u5f20\uff0c\u627e\u5230\u4e0b\u4e00\u4e2a\u8986\u76d6\u7a97\u53e3 \"DOBECODEBA\"...\r\n\u2192 \u6700\u7ec8\u6700\u4f18\u89e3\u662f \"BANC\"\uff0c\u957f\u5ea6 4<\/code><\/pre>\n<\/div>\n<\/div>\n
    \n
    \u590d\u6742\u5ea6<\/h4>\n
    \n\n\n\n\n\n\n
    \u7ef4\u5ea6<\/th>\n\u590d\u6742\u5ea6<\/th>\n\u8bf4\u660e<\/th>\n<\/tr>\n<\/thead>\n
    \u65f6\u95f4<\/td>\nO(n + m)<\/td>\nn = |s|\uff0cm = |t|\uff0c\u6bcf\u4e2a\u5b57\u7b26\u6700\u591a\u8fdb\u51fa\u7a97\u53e3\u5404\u4e00\u6b21<\/td>\n<\/tr>\n
    \u7a7a\u95f4<\/td>\nO(\u2223\u03a3\u2223)<\/td>\n\u5b57\u7b26\u96c6\u5927\u5c0f\uff0cASCII \u4e0b\u56fa\u5b9a 128<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
    \n
    \u548c\u4e0a\u9898\u7684\u5bf9\u6bd4<\/h4>\n
    \n\n\n\n\n\n\n\n\n
    <\/th>\n\u6700\u957f\u4e0d\u91cd\u590d\u5b50\u4e32<\/th>\n\u6700\u5c0f\u8986\u76d6\u5b50\u4e32<\/th>\n<\/tr>\n<\/thead>\n
    \u7a97\u53e3\u76ee\u6807<\/td>\n\u65e0\u91cd\u590d\u5b57\u7b26<\/td>\n\u8986\u76d6 t \u6240\u6709\u5b57\u7b26<\/td>\n<\/tr>\n
    \u6536\u7f29\u65f6\u673a<\/td>\n\u6709\u91cd\u590d\u5c31\u6536\u7f29<\/td>\n\u6ee1\u8db3\u6761\u4ef6\u540e\u5c3d\u91cf\u6536\u7f29<\/td>\n<\/tr>\n
    \u5224\u65ad\u6761\u4ef6<\/td>\n\u96c6\u5408 contains<\/td>\nneed == 0<\/code><\/td>\n<\/tr>\n
    \u6c42\u7684\u662f<\/td>\n\u6700\u957f<\/td>\n\u6700\u77ed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
    \u4e09\u9053\u9898\uff08\u63a5\u96e8\u6c34\u3001\u6700\u957f\u4e0d\u91cd\u590d\u3001\u6700\u5c0f\u8986\u76d6\u5b50\u4e32\uff09\u8fde\u8d77\u6765\u770b\uff0c\u4f1a\u53d1\u73b0\u53cc\u6307\u9488\/\u6ed1\u52a8\u7a97\u53e3\u7684\u672c\u8d28\u662f\uff1a\u7528\u5355\u8c03\u6027\u628a O(n\u00b2) \u66b4\u529b\u679a\u4e3e\u538b\u7f29\u6210 O(n)<\/strong>\u2014\u2014\u8fd9\u662f\u9762\u8bd5\u4e2d\u6700\u503c\u5f97\u8bb2\u6e05\u695a\u7684\u4e00\u6761\u4e3b\u7ebf\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u529b\u6263\u7b2c 76 \u9898\u3002\u7ed9\u5b9a\u5b57\u7b26\u4e32 s \u548c t<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[24],"tags":[],"class_list":["post-7383","post","type-post","status-publish","format-standard","hentry","category-value_docs"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7383","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/comments?post=7383"}],"version-history":[{"count":2,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7383\/revisions"}],"predecessor-version":[{"id":7385,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7383\/revisions\/7385"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=7383"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=7383"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=7383"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}