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jiezhi
V2EX  ›  LeetCode

被 leetcode 上的靠前的答案震惊了

  •  
  •   jiezhi ·
    Jiezhi · 2018-11-13 22:35:09 +08:00 · 13274 次点击
    这是一个创建于 1961 天前的主题,其中的信息可能已经有所发展或是发生改变。

    https://leetcode.com/problems/count-and-say/description/

    好奇点开了排名第一的答案。。。。很多人也许见怪不怪了吧

    高中搞 NOIP 的时候还想过,如果有题目不会做,我就直接把题目给的输入输出给直接输出,当然并没有去做。

    class Solution:
        def countAndSay(self, n):
            """
            :type n: int
            :rtype: str
            """
            D = {1: '1', 2: '11', 3: '21', 4: '1211', 5: '111221', 6: '312211', 7: '13112221', 8: '1113213211', 9: '31131211131221', 10: '13211311123113112211', 11: '11131221133112132113212221', 12: '3113112221232112111312211312113211', 13: '1321132132111213122112311311222113111221131221', 14: '11131221131211131231121113112221121321132132211331222113112211', 15: '311311222113111231131112132112311321322112111312211312111322212311322113212221', 16: '132113213221133112132113311211131221121321131211132221123113112221131112311332111213211322211312113211', 17: '11131221131211132221232112111312212321123113112221121113122113111231133221121321132132211331121321231231121113122113322113111221131221', 18: '31131122211311123113321112131221123113112211121312211213211321322112311311222113311213212322211211131221131211132221232112111312111213111213211231131122212322211331222113112211', 19: '1321132132211331121321231231121113112221121321132122311211131122211211131221131211132221121321132132212321121113121112133221123113112221131112311332111213122112311311123112111331121113122112132113213211121332212311322113212221', 20: '11131221131211132221232112111312111213111213211231132132211211131221131211221321123113213221123113112221131112311332211211131221131211132211121312211231131112311211232221121321132132211331121321231231121113112221121321133112132112312321123113112221121113122113121113123112112322111213211322211312113211', 21: '311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122211311122122111312211213211312111322211213211321322113311213212322211231131122211311123113223112111311222112132113311213211221121332211211131221131211132221232112111312111213111213211231132132211211131221232112111312211213111213122112132113213221123113112221131112311311121321122112132231121113122113322113111221131221', 22: '132113213221133112132123123112111311222112132113311213211231232112311311222112111312211311123113322112132113213221133122112231131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112131221123113111231121113311211131221121321131211132221123113112211121312211231131122211211133112111311222112111312211312111322211213211321322113311213211331121113122122211211132213211231131122212322211331222113112211', 23: 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'11131221131211132221232112111312111213111213211231132132211211131221232112111312211213111213122112132113213221123113112221133112132123222112111312211312112213211231132132211211131221131211132221121311121312211213211312111322211213211321322113311213212322211231131122211311123113223112111311222112132113311213211221121332211211131221131211132221231122212213211321322112311311222113311213212322211211131221131211132221232112111312111213322112131112131221121321131211132221121321132132212321121113121112133221121321132132211331121321231231121113112221121321133112132112211213322112311311222113111231133211121312211231131122211322311311222112111312211311123113322112132113212231121113112221121321132122211322212221121123222112111312211312111322212321121113121112131112132112311321322112111312212321121113122112131112131221121321132132211231131122111213122112311311222113111221131221221321132132211331121321231231121113112221121321133112132112211213322112311311222113111231133211121312211231131122211322311311222112111312211311123113322112132113212231121113112221121321132122211322212221121123222112311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111221132221231221132221222112112322211211131221131211132221232112111312111213111213211231132132211211131221232112111312211213111213122112132113213221123113112221133112132123222112111312211312111322212321121113121112133221132211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112132132112211131221131211132221121321132132212321121113121112133221123113112221131112311332111213211322111213111213211231131211132211121311222113321132211221121332211213211321322113311213212312311211131122211213211331121321123123211231131122211211131221131112311332211213211321223112111311222112132113213221123123211231132132211231131122211311123113322112111312211312111322111213122112311311123112112322211213211321322113312211223113112221121113122113111231133221121321132132211331121321232221123123211231132132211231131122211331121321232221123113112221131112311332111213122112311311123112112322211211131221131211132221232112111312211322111312211213211312111322211231131122111213122112311311221132211221121332211213211321322113311213212312311211131211131221223113112221131112311332211211131221131211132211121312211231131112311211232221121321132132211331121321231231121113112221121321133112132112211213322112312321123113213221123113112221133112132123222112311311222113111231132231121113112221121321133112132112211213322112311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311221132211221121332211211131221131211132221232112111312111213111213211231132132211211131221232112111312211213111213122112132113213221123113112221133112132123222112111312211312111322212311222122132113213221123113112221133112132123222112311311222113111231133211121321132211121311121321122112133221123113112221131112311332211322111312211312111322212321121113121112133221121321132132211331121321231231121113112221121321132122311211131122211211131221131211322113322112111312211322132113213221123113112221131112311311121321122112132231121113122113322113111221131221', 30: '3113112221131112311332111213122112311311123112111331121113122112132113121113222112311311221112131221123113112221121113311211131122211211131221131211132221121321132132212321121113121112133221123113112221131112212211131221121321131211132221123113112221131112311332211211133112111311222112111312211311123113322112111312211312111322212321121113121112133221121321132132211331121321132213211231132132211211131221232112111312212221121123222112311311222113111231133211121321321122111312211312111322211213211321322123211211131211121332211231131122211311123113321112131221123113111231121123222112111331121113112221121113122113111231133221121113122113121113221112131221123113111231121123222112111312211312111322212321121113121112131112132112311321322112111312212321121113122122211211232221121321132132211331121321231231121113112221121321132132211322132113213221123113112221133112132123222112111312211312112213211231132132211211131221131211322113321132211221121332211231131122211311123113321112131221123113111231121113311211131221121321131211132221123113112211121312211231131122211211133112111311222112111312211312111322211213211321223112111311222112132113213221133122211311221122111312211312111322212321121113121112131112132112311321322112111312212321121113122122211211232221121321132132211331121321231231121113112221121321132132211322132113213221123113112221133112132123222112111312211312112213211231132132211211131221131211322113321132211221121332211213211321322113311213212312311211131122211213211331121321123123211231131122211211131221131112311332211213211321223112111311222112132113213221123123211231132132211231131122211311123113322112111312211312111322111213122112311311123112112322211213211321322113312211223113112221121113122113111231133221121321132132211331222113321112131122211332113221122112133221123113112221131112311332111213122112311311123112111331121113122112132113121113222112311311221112131221123113112221121113311211131122211211131221131211132221121321132132212321121113121112133221123113112221131112311332111213122112311311123112112322211322311311222113111231133211121312211231131112311211232221121113122113121113222123211211131221132211131221121321131211132221123113112211121312211231131122113221122112133221121321132132211331121321231231121113121113122122311311222113111231133221121113122113121113221112131221123113111231121123222112132113213221133112132123123112111312211322311211133112111312211213211311123113223112111321322123122113222122211211232221121113122113121113222123211211131211121311121321123113213221121113122123211211131221121311121312211213211321322112311311222113311213212322211211131221131211221321123113213221121113122113121113222112131112131221121321131211132221121321132132211331121321232221123113112221131112311322311211131122211213211331121321122112133221121113122113121113222123112221221321132132211231131122211331121321232221121113122113121113222123211211131211121332211213111213122112132113121113222112132113213221232112111312111213322112132113213221133112132123123112111311222112132113311213211221121332211231131122211311123113321112131221123113112221132231131122211211131221131112311332211213211321223112111311222112132113212221132221222112112322211211131221131211132221232112111312111213111213211231131112311311221122132113213221133112132123222112311311222113111231132231121113112221121321133112132112211213322112111312211312111322212321121113121112131112132112311321322112111312212321121113122122211211232221121311121312211213211312111322211213211321322123211211131211121332211213211321322113311213211322132112311321322112111312212321121113122122211211232221121321132132211331121321231231121113112221121321133112132112312321123113112221121113122113111231133221121321132122311211131122211213211321222113222122211211232221123113112221131112311332111213122112311311123112111331121113122112132113121113222112311311221112131221123113112221121113311211131122211211131221131211132221121321132132212321121113121112133221123113112221131112311332111213213211221113122113121113222112132113213221232112111312111213322112132113213221133112132123123112111312211322311211133112111312212221121123222112132113213221133112132123222113223113112221131112311332111213122112311311123112112322211211131221131211132221232112111312111213111213211231132132211211131221131211221321123113213221123113112221131112211322212322211231131122211322111312211312111322211213211321322113311213211331121113122122211211132213211231131122212322211331222113112211'}
        
            return D[n]
    
    第 1 条附言  ·  2018-11-14 16:56:54 +08:00
    大家已经不是见怪不怪了,而是习以为常了。

    个人觉得在 LeetCode 这个平台,更多的是研究解题思路,写出优雅的解法。

    正文中的例子,虽然能通过测试,但不具有泛化性,可以说在生产过程中基本毫无用处,应该算是违背平台的初衷了吧。
    15 条回复    2018-11-14 16:43:17 +08:00
    huntzhan
        1
    huntzhan  
       2018-11-13 22:46:38 +08:00
    leetcode 打表还行
    24bit
        2
    24bit  
       2018-11-13 22:48:33 +08:00
    习惯就好
    111qqz
        3
    111qqz  
       2018-11-13 22:49:39 +08:00
    搞过 noip 应该知道骗分和打表呀(
    vegito2002
        4
    vegito2002  
       2018-11-13 23:40:24 +08:00
    leetcode contest 比赛的时候这种人多了去了, 见一个举报一个
    xxx749
        5
    xxx749  
       2018-11-13 23:44:12 +08:00 via Android
    这题目什么意思,没看懂
    nililnellaf
        6
    nililnellaf  
       2018-11-13 23:44:50 +08:00
    noip 骗分不奇怪啊 手算也只能算个小数据
    zhengjian
        7
    zhengjian  
       2018-11-13 23:47:53 +08:00
    yuikns
        8
    yuikns  
       2018-11-13 23:54:21 +08:00 via iPhone   ❤️ 1
    @xxx749 每一步都是上一步的描述

    1
    一个 1,即 11
    二个 1,即 21
    一个 2,一个 1,即 1211
    ... 以此类推
    Xs0ul
        9
    Xs0ul  
       2018-11-14 00:02:08 +08:00
    @zhengjian #7 我也看过这个,必胜策略就是比奇偶两列那个多,然后只取多的那个
    xxx749
        10
    xxx749  
       2018-11-14 00:48:14 +08:00 via Android
    🤥正则的性能这么差的吗? JS 才 beats 15.11
    yuikns
        11
    yuikns  
       2018-11-14 01:18:31 +08:00
    刚发现这道题我是做过的。
    两年前是这么写的 (0ms):

    void i2v(int i, vector<int> & r) {
    int offset = r.size() - 1;
    while (i > 0) {
    r.push_back(i % 10);
    i /= 10;
    }
    for (int j = offset; j < (r.size() - offset) / 2; j++) {
    int t = r[j];
    r[j] = r[r.size() - 1 - j - offset];
    r[r.size() - 1 - j - offset] = t;
    }
    }

    vector<int> gen(vector<int> &c, int n) {
    if (n > 0) {
    vector<int> r;
    int vv = c[0];
    int vc = 0;
    for (int i = 0; i < c.size(); i++) {
    if (c[i] == vv) {
    vc++;
    } else {
    i2v(vc,r);
    r.push_back(vv);
    vc = 1;
    vv = c[i];
    }
    }
    if (vc > 0) {
    i2v(vc,r);
    r.push_back(vv);
    }
    return gen(r, n - 1);
    } else {
    return c;
    }
    }

    string countAndSay(int n) {
    vector<int> c;
    c.push_back(1);
    vector<int> r = gen(c, n - 1);
    char str[r.size() + 1];
    str[r.size()] = '\0';
    for (int i = 0; i < r.size(); i++) {
    //s += (char)(r[i] + '0');
    str[i] = r[i] + '0';
    }
    return string(str);
    }


    现在是这么写的 (4ms):

    string countAndSay(int n) {
    if(n <= 1) return "1";
    string prev = countAndSay(n-1);
    string buff = "";
    char ci = '\0';
    int cc = 0;
    for(auto c : prev) {
    if(c != ci) {
    if(ci != '\0') {
    buff += to_string(cc);
    buff += ci;
    }
    ci = c;
    cc = 1;
    } else {
    cc ++;
    }
    }
    if (cc > 0) {
    buff += to_string(cc);
    buff += ci;
    }
    return buff;
    }

    越来越水了...
    elikoi17
        12
    elikoi17  
       2018-11-14 04:00:16 +08:00 via Android
    打表蒙点是正常操作吧。。。
    echoZero
        13
    echoZero  
       2018-11-14 09:51:05 +08:00
    打表算是个正常的操作 有时候
    case 优先 打表是可以过得
    nyaruko
        14
    nyaruko  
       2018-11-14 14:13:26 +08:00
    noip 确实有这么骗分的。中学参加过这类比赛的应该都熟悉。。

    但是 leetcode 也这么玩。有点不好吧。毕竟是锻炼算法的地方
    xmt328
        15
    xmt328  
       2018-11-14 16:43:17 +08:00
    打表也算是一个骗分的经典操作了
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