{"id":881,"date":"2025-10-03T18:01:57","date_gmt":"2025-10-03T10:01:57","guid":{"rendered":"https:\/\/www.guanhaobo.cn\/?p=881"},"modified":"2025-10-03T18:01:57","modified_gmt":"2025-10-03T10:01:57","slug":"leetcode-560-%e5%92%8c%e4%b8%ba-k-%e7%9a%84%e5%ad%90%e6%95%b0%e7%bb%84","status":"publish","type":"post","link":"https:\/\/www.guanhaobo.cn\/?p=881","title":{"rendered":"LeetCode 560 \u2013 \u548c\u4e3a K \u7684\u5b50\u6570\u7ec4"},"content":{"rendered":"

\u9898\u76ee\u63cf\u8ff0<\/h1>\n

\u7ed9\u4f60\u4e00\u4e2a\u6574\u6570\u6570\u7ec4 nums \u548c\u4e00\u4e2a\u6574\u6570 k \uff0c\u8bf7\u4f60\u7edf\u8ba1\u5e76\u8fd4\u56de \u8be5\u6570\u7ec4\u4e2d\u548c\u4e3a k \u7684\u5b50\u6570\u7ec4\u7684\u4e2a\u6570 \u3002<\/p>\n

\u5b50\u6570\u7ec4\u662f\u6570\u7ec4\u4e2d\u5143\u7d20\u7684\u8fde\u7eed\u975e\u7a7a\u5e8f\u5217\u3002<\/p>\n

\u793a\u4f8b 1\uff1a<\/p>\n

\u8f93\u5165\uff1anums = [1,1,1], k = 2
\n\u8f93\u51fa\uff1a2
\n\u793a\u4f8b 2\uff1a<\/p>\n

\u8f93\u5165\uff1anums = [1,2,3], k = 3
\n\u8f93\u51fa\uff1a2<\/p>\n

\u63d0\u793a\uff1a<\/p>\n

1 <= nums.length <= 2 * 10^4
\n-1000 <= nums[i] <= 1000
\n-10^7 <= k <= 10^7<\/p>\n

\u9898\u76ee\u5206\u6790<\/h1>\n

\u6570\u7ec4\u4e2d\u7684\u6570\u5b57\u5b58\u5728\u8d1f\u6570\uff0c\u56e0\u6b64\u4e0d\u80fd\u4f7f\u7528\u6ed1\u52a8\u7a97\u53e3\u6765\u89e3\u51b3\u3002
\n\u524d\u7f00\u548c + \u54c8\u5e0c\u8868\u3002
\n\u5047\u8bbe pre[i] \u8868\u793a\u4ece 0 \u5230 i \u7684\u5143\u7d20\u7684\u548c\uff0c\u90a3\u4e48 \u4ece l \u5230 r \u7684\u548c\u5c31\u7b49\u4e8e pre[r] – pre[l-1]\u3002\u4ece\u5de6\u5230\u53f3\u679a\u4e3e\u6570\u7ec4\uff0c\u540c\u65f6\u628a\u524d\u7f00\u548c\u6dfb\u52a0\u5230\u54c8\u5e0c\u8868\u4e2d\uff08\u53ef\u80fd\u5b58\u5728\u91cd\u590d\u503c\uff0c\u56e0\u6b64key\u662f\u524d\u7f00\u548c\uff0cvalue\u662f\u6570\u91cf\uff09\u3002
\n\u5bf9\u4e8e\u6bcf\u4e2a r\uff0c\u90fd\u5b58\u5728\u4e24\u79cd\u60c5\u51b5\u6ee1\u8db3\u5b50\u6570\u7ec4\u548c\u4e3ak\uff1a
\n– l = 0\uff0c\u4e14 pre[r] = k
\n– l > 0\uff0c\u54c8\u5e0c\u8868\u4e2d\u5b58\u5728 pre[r] – k<\/p>\n

Java<\/h1>\n
public int subarraySum(int[] nums, int k) {\n    int pre = 0;\n    int ans = 0;\n    HashMap<Integer, Integer> map = new HashMap<>();\n    for (int num : nums) {\n        pre += num;\n        if (pre == k) {\n            ans++;\n        }\n        ans += map.getOrDefault(pre - k, 0);\n\n        map.put(pre, map.getOrDefault(pre, 0) + 1);\n    }\n    return ans;\n}\n<\/code><\/pre>\n
Kotlin<\/h1>\n
fun subarraySum(nums: IntArray, k: Int): Int {\n    var ans = 0\n    var pre = 0\n    val map = HashMap<Int, Int>()\n    for (r in nums.indices) {\n        pre += nums[r]\n        if (pre == k) {\n            ans++\n        }\n        ans += map[pre - k] ?: 0\n\n        map[pre] = (map[pre] ?: 0) + 1\n    }\n    return ans\n}\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
\u9898\u76ee\u63cf\u8ff0 \u7ed9\u4f60\u4e00\u4e2a\u6574\u6570\u6570\u7ec4 nums \u548c\u4e00\u4e2a\u6574\u6570 k \uff0c\u8bf7\u4f60\u7edf\u8ba1\u5e76\u8fd4\u56de \u8be5\u6570\u7ec4\u4e2d\u548c\u4e3a k \u7684\u5b50\u6570\u7ec4\u7684\u4e2a\u6570 \u3002  […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[20,78,74],"class_list":["post-881","post","type-post","status-publish","format-standard","hentry","category-algo","tag-leetcode","tag-78","tag-74"],"_links":{"self":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts\/881","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=881"}],"version-history":[{"count":1,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts\/881\/revisions"}],"predecessor-version":[{"id":882,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=\/wp\/v2\/posts\/881\/revisions\/882"}],"wp:attachment":[{"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=881"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=881"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.guanhaobo.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=881"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}