不好好写代码，就只能回去当总理了

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不好好写代码，就只能回去当总理了

21CTO

资讯 0 3359 2020-04-29 12:04:12

最近，《Hands-on Scala Programming》的作者李浩毅在程序员圈子引发热议。原来他就是新加坡总理李显龙的儿子。

（格子衫衬衣是不是很眼熟？）
据公开信息显示，李浩毅出于 1989 年，毕业于 MIT，计算机科学和工程学位。他是 Scala 社区的主要贡献者。
李浩毅的个人网站上自称，其开源项目在 Github 上有超过 10,000 Star，每个月的下载次数超过 7,000,000 次。自称擅长用 Scala 来构建分布式后端系统、高性能 web 应用程序等。
有网友感叹，他一直关注的技术博主，原来是这样的身份背景。「这是我人生接触的第二个家里比我有权家里黄金遍地智商比我强还比我努力的人！」

还有网友调侃说，要是李浩毅不好好写代码，就只有回去当坡县县长了。

新加坡总理也是会编程的
其实现任总理李显龙，也是有计算机科学文凭的。

他在英国剑桥大学三一学院修读数学，1973 年拿过数学尖子生「Senior Wrangler」头衔，1974 年荣获数学一等荣誉及计算机科学文凭（优异）。
2015 年 5 月，李显龙曾经在一次创业者论坛上透露，他最后编写的程序是一个解决数独问题的程序。

（防杠提醒：截图中有源码链接，可查证）
在帖子中，李显龙除了解释程序之外，还公开了数独程序的完整源码。有兴趣的童鞋，请看：

    = '1' && ch <= '9') <br/>                InitEntry(i, j, ch - '0');<br/>         }<br/>     }<br/><br/>     PrintArray();<br/>}<br/><br/><br/>void PrintStats()<br/>{<br/>    int i, j, S;<br/><br/>    printf("\nLevel Counts:\n\n");<br/><br/>    S = 0;<br/>    while (LevelCount[S] == 0) S++;<br/><br/>    i = 0;<br/><br/>    while (S < 81) {<br/>          int Seq = Sequence[S];<br/>          printf("(%d, %d):%4d ", Seq / 9 + 1, Seq % 9 + 1, LevelCount[S]);<br/>          if (i++ > 4){<br/>             printf("\n");<br/>             i = 0;<br/>          }<br/>          S++;<br/>    }<br/><br/>    printf("\n\nCount = %d\n", Count);<br/>}<br/><br/><br/>void Succeed()<br/>{<br/>     PrintArray();<br/>     PrintStats();<br/>}<br/><br/><br/>int NextSeq(int S)<br/>{<br/>    int S2, Square, Possibles, BitCount;<br/>    int T, MinBitCount = 100;<br/><br/>    for (T = S; T < 81; T++) {<br/>        Square = Sequence[T];<br/>        Possibles = Block[InBlock[Square]] & Row[InRow[Square]] & Col[InCol[Square]];<br/>        BitCount = 0;<br/>        while (Possibles) {<br/>           Possibles &= ~(Possibles & -Possibles);<br/>           BitCount++;<br/>        }<br/><br/>        if (BitCount < MinBitCount) {<br/>           MinBitCount = BitCount;<br/>           S2 = T;<br/>        }<br/>    }<br/><br/>    return S2;<br/>}<br/><br/><br/>void Place(int S)<br/>{<br/>    LevelCount[S]++;<br/>    Count++;<br/><br/>    if (S >= 81) {<br/>       Succeed();<br/>       return;<br/>    }<br/><br/>    int S2 = NextSeq(S);<br/>    SwapSeqEntries(S, S2);<br/><br/>    int Square = Sequence[S];<br/><br/>    int   BlockIndex = InBlock[Square],<br/>          RowIndex = InRow[Square],<br/>          ColIndex = InCol[Square];<br/><br/>    int  Possibles = Block[BlockIndex] & Row[RowIndex] & Col[ColIndex];<br/>    while (Possibles) {<br/>          int valbit = Possibles & (-Possibles); // Lowest 1 bit in Possibles<br/>          Possibles &= ~valbit;<br/>          Entry[Square] = valbit;<br/>          Block[BlockIndex] &= ~valbit;<br/>          Row[RowIndex] &= ~valbit;<br/>          Col[ColIndex] &= ~valbit;<br/>             <br/>          Place(S + 1);<br/><br/>          Entry[Square] = BLANK; // Could be moved out of the loop<br/>          Block[BlockIndex] |= valbit;<br/>          Row[RowIndex] |= valbit;<br/>          Col[ColIndex] |= valbit;<br/>  }<br/><br/>    SwapSeqEntries(S, S2);<br/>}<br/><br/><br/>int main(int argc, char* argv[])<br/>{<br/>   int i, j, Square;<br/><br/> for (i = 0; i < 9; i++)<br/>        for (j = 0; j < 9; j++) {<br/>          Square = 9 * i + j;<br/>            InRow[Square] = i;<br/>         InCol[Square] = j;<br/>         InBlock[Square] = (i / 3) * 3 + ( j / 3);<br/>      }<br/><br/><br/>    for (Square = 0; Square < 81; Square++) {<br/>        Sequence[Square] = Square;<br/>       Entry[Square] = BLANK;<br/>        LevelCount[Square] = 0;<br/>    }<br/><br/>  for (i = 0; i < 9; i++) <br/>       Block[i] = Row[i] = Col[i] = ONES;<br/><br/>    ConsoleInput();<br/>    Place(SeqPtr);<br/>    printf("\n\nTotal Count = %d\n", Count);<br/><br/>   return 0;<br/>}" data-wx-hl-lang="c" data-wx-hl-style="atom-one-dark" style="margin-right: 0.15em;margin-left: 0.15em;padding: 0.5em;max-width: 100%;font-size: 0.85em;font-family: Consolas, Menlo, Courier, monospace;overflow: auto;display: block;color: rgb(171, 178, 191);text-size-adjust: none;min-width: 400px;background: none 0% 0% / auto repeat scroll padding-box border-box rgb(40, 44, 52);box-sizing: border-box !important;overflow-wrap: break-word !important;">#include "stdio.h"  



    int InBlock[81], InRow[81], InCol[81];  



    const int BLANK = 0;  

    const int ONES = 0x3fe;   // Binary 1111111110  



    int Entry[81];  // Records entries 1-9 in the grid, as the corresponding bit set to 1  

    int Block[9], Row[9], Col[9];  // Each int is a 9-bit array  



    int SeqPtr = 0;  

    int Sequence[81];  



    int Count = 0;  

    int LevelCount[81];  





    void SwapSeqEntries(int S1, int S2)  

    {  

         int temp = Sequence[S2];  

         Sequence[S2] = Sequence[S1];  

         Sequence[S1] = temp;  

    }  





    void InitEntry(int i, int j, int val)  

    {  

       int Square = 9 * i + j;  

       int valbit = 1 << val;  

         int SeqPtr2;  



         // add suitable checks for data consistency  



       Entry[Square] = valbit;  

       Block[InBlock[Square]] &= ~valbit;  

       Col[InCol[Square]] &= ~valbit; // Simpler Col[j] &= ~valbit;  

       Row[InRow[Square]] &= ~valbit; // Simpler Row[i] &= ~valbit;  



         SeqPtr2 = SeqPtr;  

         while (SeqPtr2 < 81 && Sequence[SeqPtr2] != Square)  

               SeqPtr2++ ;  



         SwapSeqEntries(SeqPtr, SeqPtr2);  

         SeqPtr++;  

    }  





    void PrintArray()  

    {  

         int i, j, valbit, val, Square;  

         char ch;  



         Square = 0;  



         for (i = 0; i < 9; i++) {  

             if (i % 3 == 0) putc('\n', stdout);  

             for (j = 0; j < 9; j++) {  

                 if (j % 3 == 0) putc(' ', stdout);  

                 valbit = Entry[Square++];  

                 if (valbit == 0) ch = '-';  

                 else {  

                     for (val = 1; val <= 9; val++)  

                         if (valbit == (1 << val)) {  

                            ch = '0' + val;  

                            break;  

                         }  

                 }  

                 putc(ch,stdout);  

             }  

             putc ('\n', stdout);  

         }  

    }  





    void ConsoleInput()  

    {  

         int i, j;  

         char InputString[80];  



         for (i = 0; i < 9; i++) {  

             printf("Row[%d] : ", i + 1);  

             scanf("%s", InputString);  



             for (j = 0; j < 9; j++) {  

                 char ch = InputString[j];  

                 if (ch >= '1' && ch <= '9')  

                    InitEntry(i, j, ch - '0');  

             }  

         }  



         PrintArray();  

    }  





    void PrintStats()  

    {  

        int i, j, S;  



        printf("\nLevel Counts:\n\n");  



        S = 0;  

        while (LevelCount[S] == 0) S++;  



        i = 0;  



        while (S < 81) {  

              int Seq = Sequence[S];  

              printf("(%d, %d):%4d ", Seq / 9 + 1, Seq % 9 + 1, LevelCount[S]);  

              if (i++ > 4){  

                 printf("\n");  

                 i = 0;  

              }  

              S++;  

        }  



        printf("\n\nCount = %d\n", Count);  

    }  





    void Succeed()  

    {  

         PrintArray();  

         PrintStats();  

    }  





    int NextSeq(int S)  

    {  

        int S2, Square, Possibles, BitCount;  

        int T, MinBitCount = 100;  



        for (T = S; T < 81; T++) {  

            Square = Sequence[T];  

            Possibles = Block[InBlock[Square]] & Row[InRow[Square]] & Col[InCol[Square]];  

            BitCount = 0;  

            while (Possibles) {  

               Possibles &= ~(Possibles & -Possibles);  

               BitCount++;  

            }  



            if (BitCount < MinBitCount) {  

               MinBitCount = BitCount;  

               S2 = T;  

            }  

        }  



        return S2;  

    }  





    void Place(int S)  

    {  

        LevelCount[S]++;  

        Count++;  



        if (S >= 81) {  

           Succeed();  

           return;  

        }  



        int S2 = NextSeq(S);  

        SwapSeqEntries(S, S2);  



        int Square = Sequence[S];  



        int   BlockIndex = InBlock[Square],  

          RowIndex = InRow[Square],  

          ColIndex = InCol[Square];  



        int   Possibles = Block[BlockIndex] & Row[RowIndex] & Col[ColIndex];  

        while (Possibles) {  

              int valbit = Possibles & (-Possibles); // Lowest 1 bit in Possibles  

              Possibles &= ~valbit;  

              Entry[Square] = valbit;  

              Block[BlockIndex] &= ~valbit;  

              Row[RowIndex] &= ~valbit;  

              Col[ColIndex] &= ~valbit;  



              Place(S + 1);  



              Entry[Square] = BLANK; // Could be moved out of the loop  

              Block[BlockIndex] |= valbit;  

              Row[RowIndex] |= valbit;  

              Col[ColIndex] |= valbit;  

      }  



        SwapSeqEntries(S, S2);  

    }  





    int main(int argc, char* argv[])  

    {  

      int i, j, Square;  



      for (i = 0; i < 9; i++)  

        for (j = 0; j < 9; j++) {  

          Square = 9 * i + j;  

          InRow[Square] = i;  

          InCol[Square] = j;  

          InBlock[Square] = (i / 3) * 3 + ( j / 3);  

        }  





      for (Square = 0; Square < 81; Square++) {  

            Sequence[Square] = Square;  

        Entry[Square] = BLANK;  

            LevelCount[Square] = 0;  

        }  



      for (i = 0; i < 9; i++)  

        Block[i] = Row[i] = Col[i] = ONES;  



        ConsoleInput();  

        Place(SeqPtr);  

        printf("\n\nTotal Count = %d\n", Count);  



      return 0;  

    }