{"id":297,"date":"2020-09-26T10:19:00","date_gmt":"2020-09-26T02:19:00","guid":{"rendered":"http:\/\/39.96.58.60\/?p=297"},"modified":"2022-10-18T16:43:53","modified_gmt":"2022-10-18T08:43:53","slug":"leetcode-18-%e5%9b%9b%e6%95%b0%e4%b9%8b%e5%92%8c","status":"publish","type":"post","link":"http:\/\/www.yatenglg.cn\/blog\/?p=297","title":{"rendered":"Leetcode 18. \u56db\u6570\u4e4b\u548c"},"content":{"rendered":"<p>\u7ed9\u5b9a\u4e00\u4e2a\u5305\u542b&nbsp;<em>n<\/em> \u4e2a\u6574\u6570\u7684\u6570\u7ec4&nbsp;<code>nums<\/code>&nbsp;\u548c\u4e00\u4e2a\u76ee\u6807\u503c&nbsp;<code>target<\/code>\uff0c\u5224\u65ad&nbsp;<code>nums<\/code>&nbsp;\u4e2d\u662f\u5426\u5b58\u5728\u56db\u4e2a\u5143\u7d20 <em>a\uff0c<\/em><em>b\uff0cc<\/em>&nbsp;\u548c <em>d<\/em>&nbsp;\uff0c\u4f7f\u5f97&nbsp;<em>a<\/em> + <em>b<\/em> + <em>c<\/em> + <em>d<\/em>&nbsp;\u7684\u503c\u4e0e&nbsp;<code>target<\/code>&nbsp;\u76f8\u7b49\uff1f\u627e\u51fa\u6240\u6709\u6ee1\u8db3\u6761\u4ef6\u4e14\u4e0d\u91cd\u590d\u7684\u56db\u5143\u7ec4\u3002<\/p>\n<p><strong>\u6ce8\u610f\uff1a<\/strong><\/p>\n<p>\u7b54\u6848\u4e2d\u4e0d\u53ef\u4ee5\u5305\u542b\u91cd\u590d\u7684\u56db\u5143\u7ec4\u3002<\/p>\n<p><strong>\u793a\u4f8b\uff1a<\/strong><\/p>\n<pre>\u7ed9\u5b9a\u6570\u7ec4 nums = [1, 0, -1, 0, -2, 2]\uff0c\u548c target = 0\u3002\n\n\n\n\u6ee1\u8db3\u8981\u6c42\u7684\u56db\u5143\u7ec4\u96c6\u5408\u4e3a\uff1a\n\n[\n\n  [-1,  0, 0, 1],\n\n  [-2, -1, 1, 2],\n\n  [-2,  0, 0, 2]\n\n]\n\n<\/pre>\n<p>**\u96be\u5ea6**: Medium<\/p>\n<p>**\u6807\u7b7e**: \u6570\u7ec4\u3001 \u54c8\u5e0c\u8868\u3001 \u53cc\u6307\u9488\u3001<\/p>\n<div class=\"hcb_wrap\">\n<pre class=\"prism undefined-numbers lang-python\" data-lang=\"Python\"><code>\n# -*- coding: utf-8 -*-\n# @Author  : LG\n\n\"\"\"\n\u884c\u7528\u65f6\uff1a1808 ms, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8614.35% \u7684\u7528\u6237\n\u5185\u5b58\u6d88\u8017\uff1a13.5 MB, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8697.14% \u7684\u7528\u6237\n\n\u89e3\u9898\u601d\u8def\uff1a\n    \u53cc\u6307\u9488\u6cd5\uff0c\u603b\u4f53\u601d\u8def\u540c\u4e09\u6570\u6c42\u548c\n\n      i  j l                                      r\n    [-7,-5,0,7,1,1,-10,-2,7,7,-2,-6,0,-10,-5,7,-8,5], 28\n    \u5916\u5c42i, j\u53cc\u5faa\u73af\uff0c l, r\u53cc\u6307\u9488\u5206\u522b\u6307\u5411\u5934\u5c3e\u3002\n\"\"\"\nclass Solution:\n    def fourSum(self, nums: List[int], target: int) -&gt; List[List[int]]:\n        nums.sort()\n        n = len(nums)\n        if n &lt; 4:       # \u957f\u5ea6\u5c0f\u4e8e4\uff0c\u76f4\u63a5\u8fd4\u56de[]\n            return []\n\n        result = []\n        now_i = None\n        for i in range(n):\n            if nums[i] == now_i:    # i\u53bb\u91cd\n                continue\n            now_i = nums[i]\n\n            now_j = None\n            for j in range(i + 1, n):\n                if nums[j] == now_j:    # j\u53bb\u91cd\n                    continue\n                now_j = nums[j]\n\n                l, r = j + 1, n - 1     # \u53cc\u6307\u9488\u5206\u522b\u6307\u5411\u5269\u4f59\u5b57\u7b26\u4e32\u7684\u5934\u5c3e\n                while l &lt; r:\n                    if nums[i] + nums[j] + nums[l] + nums[r] == target:     # \u82e5\u76f8\u7b49\n                        result.append([nums[i], nums[j], nums[l], nums[r]])\n                        while l &lt; r and nums[l] == nums[l + 1]: # \u5de6\u6307\u9488\u53bb\u91cd\n                            l += 1\n                        while l &lt; r and nums[r] == nums[r - 1]: # \u53f3\u6307\u9488\u53bb\u91cd\n                            r -= 1\n                        l += 1  # \u7531\u4e8e\u76f8\u7b49\uff0c\u4e14\u5df2\u6392\u5e8f\u53bb\u91cd\u3002\u5de6\u53f3\u6307\u9488\u53ef\u540c\u65f6\u5411\u4e2d\u95f4\u79fb\u52a8\n                        r -= 1\n                    elif nums[i] + nums[j] + nums[l] + nums[r] &lt; target:    # \u548c\u5c0f\uff0c\u79fb\u52a8\u5de6\u6307\u9488\n                        l += 1\n                    else:   # \u548c\u5927\uff0c\u79fb\u52a8\u53f3\u6307\u9488\n                        r -= 1\n        return result\n\n\"\"\"\n\u6267\u884c\u7528\u65f6\uff1a124 ms, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8676.55% \u7684\u7528\u6237\n\u5185\u5b58\u6d88\u8017\uff1a13.7 MB, \u5728\u6240\u6709 Python3 \u63d0\u4ea4\u4e2d\u51fb\u8d25\u4e8652.62% \u7684\u7528\u6237\n\n\u89e3\u9898\u601d\u8def\uff1a\n    \u5bf9\u4e0a\u8ff0\u4ee3\u7801\u8fdb\u884c\u4f18\u5316\u540e\uff0c\u901f\u5ea6\u8fdb\u4e00\u6b65\u63d0\u5347\n    \u53ef\u5c06\u6bcf\u6b21\u7684\u7d22\u5f15\u503c\u4fdd\u5b58\u4e0b\u6765\uff0c\u5982 num_i = nums[i]\uff0c\u514d\u53bb\u6bcf\u6b21\u7d22\u5f15\u5e94\u8be5\u4f1a\u66f4\u5feb\u4e00\u70b9\n\"\"\"\nclass Solution:\n    def fourSum(self, nums: List[int], target: int) -&gt; List[List[int]]:\n        nums.sort()\n        n = len(nums)\n        if n &lt; 4:\n            return []\n\n        result = []\n        now_i = None\n\n        for i in range(n - 3):\n            if nums[i] == now_i:\n                continue\n            now_i = nums[i]\n\n            if nums[i] * 4 &gt; target:    # \u5f53\u524d4\u500d\u7684\u6700\u5c0f\u503c\u5927\u4e8e\u76ee\u6807\u503c\uff0c\u5219\u540e\u7eed\u5747\u5927\u4e8e\uff0c\u8df3\u51fa\u5faa\u73af\n                break\n            if nums[i] + nums[-1] * 3 &lt; target: # \u5f53\u524d\u6700\u5c0f\u503c\u4e0e3\u500d\u7684\u6700\u5927\u503c\u7684\u548c\u5c0f\u4e8e\u76ee\u6807\u503c\uff0c\u8df3\u51fa\u672c\u6b21\u5faa\u73af\n                continue\n\n            now_j = None\n            for j in range(i + 1, n - 2):\n                if nums[j] == now_j:\n                    continue\n                now_j = nums[j]\n\n                if nums[i] + nums[j] * 3 &gt; target:  # \u4f18\u5316\n                    break\n                if nums[i] + nums[j] + nums[-1] * 2 &lt; target:   # \u4f18\u5316\n                    continue\n\n                l, r = j + 1, n - 1\n                while l &lt; r:\n                    if nums[i] + nums[j] + nums[l] + nums[r] == target:\n                        result.append([nums[i], nums[j], nums[l], nums[r]])\n                        while l &lt; r and nums[l] == nums[l + 1]:\n                            l += 1\n                        while l &lt; r and nums[r] == nums[r - 1]:\n                            r -= 1\n                        l += 1\n                        r -= 1\n                    elif nums[i] + nums[j] + nums[l] + nums[r] &lt; target:\n                        l += 1\n                    else:\n                        r -= 1\n        return result<\/code><\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u7ed9\u5b9a\u4e00\u4e2a\u5305\u542b&nbsp;n \u4e2a\u6574\u6570\u7684\u6570\u7ec4&nbsp;nums&nbsp;\u548c\u4e00\u4e2a\u76ee\u6807\u503c&nbsp;target\uff0c&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[11,1],"tags":[],"_links":{"self":[{"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts\/297"}],"collection":[{"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=297"}],"version-history":[{"count":1,"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts\/297\/revisions"}],"predecessor-version":[{"id":298,"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=\/wp\/v2\/posts\/297\/revisions\/298"}],"wp:attachment":[{"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=297"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=297"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.yatenglg.cn\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=297"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}