looknsay.c

#include <stdio.h>

/* http://www.njohnston.ca/2010/10/a-derivation-of-conways-degree-71-look-and-say-polynomial/ */
const struct sequence {
    char *seq;
    int next[7];
} SEQUENCES[] = {
    {NULL, {0}},
    {"1112", {63}},
    {"1112133", {64, 62}},
    {"111213322112", {65}},
    {"111213322113", {66}},
    {"1113", {68}},
    {"11131", {69}},
    {"111311222112", {84, 55}},
    {"111312", {70}},
    {"11131221", {71}},
    {"1113122112", {76}},
    {"1113122113", {77}},
    {"11131221131112", {82}},
    {"111312211312", {78}},
    {"11131221131211", {79}},
    {"111312211312113211", {80}},
    {"111312211312113221133211322112211213322112", {81, 29, 91}},
    {"111312211312113221133211322112211213322113", {81, 29, 90}},
    {"11131221131211322113322112", {81, 30}},
    {"11131221133112", {75, 29, 92}},
    {"1113122113322113111221131221", {75, 32}},
    {"11131221222112", {72}},
    {"111312212221121123222112", {73}},
    {"111312212221121123222113", {74}},
    {"11132", {83}},
    {"1113222", {86}},
    {"1113222112", {87}},
    {"1113222113", {88}},
    {"11133112", {89, 92}},
    {"12", {1}},
    {"123222112", {3}},
    {"123222113", {4}},
    {"12322211331222113112211", {2, 61, 29, 85}},
    {"13", {5}},
    {"131112", {28}},
    {"13112221133211322112211213322112", {24, 33, 61, 29, 91}},
    {"13112221133211322112211213322113", {24, 33, 61, 29, 90}},
    {"13122112", {7}},
    {"132", {8}},
    {"13211", {9}},
    {"132112", {10}},
    {"1321122112", {21}},
    {"132112211213322112", {22}},
    {"132112211213322113", {23}},
    {"132113", {11}},
    {"1321131112", {19}},
    {"13211312", {12}},
    {"1321132", {13}},
    {"13211321", {14}},
    {"132113212221", {15}},
    {"13211321222113222112", {18}},
    {"1321132122211322212221121123222112", {16}},
    {"1321132122211322212221121123222113", {17}},
    {"13211322211312113211", {20}},
    {"1321133112", {6, 61, 29, 92}},
    {"1322112", {26}},
    {"1322113", {27}},
    {"13221133112", {25, 29, 92}},
    {"1322113312211", {25, 29, 67}},
    {"132211331222113112211", {25, 29, 85}},
    {"13221133122211332", {25, 29, 68, 61, 29, 89}},
    {"22", {61}},
    {"3", {33}},
    {"3112", {40}},
    {"3112112", {41}},
    {"31121123222112", {42}},
    {"31121123222113", {43}},
    {"3112221", {38, 39}},
    {"3113", {44}},
    {"311311", {48}},
    {"31131112", {54}},
    {"3113112211", {49}},
    {"3113112211322112", {50}},
    {"3113112211322112211213322112", {51}},
    {"3113112211322112211213322113", {52}},
    {"311311222", {47, 38}},
    {"311311222112", {47, 55}},
    {"311311222113", {47, 56}},
    {"3113112221131112", {47, 57}},
    {"311311222113111221", {47, 58}},
    {"311311222113111221131221", {47, 59}},
    {"31131122211311122113222", {47, 60}},
    {"3113112221133112", {47, 33, 61, 29, 92}},
    {"311312", {45}},
    {"31132", {46}},
    {"311322113212221", {53}},
    {"311332", {38, 29, 89}},
    {"3113322112", {38, 30}},
    {"3113322113", {38, 31}},
    {"312", {34}},
    {"312211322212221121123222113", {36}},
    {"312211322212221121123222112", {35}},
    {"32112", {37}}
};

const int BASE = 8;

void evolve(int seq, int n)
{
    if (n <= 0) {
        printf(SEQUENCES[seq].seq);
    } else {
        for (const int *next = SEQUENCES[seq].next; *next; next++)
            evolve(*next, n - 1);
    }
}

int main()
{
    int n;
    scanf("%d\n", &n);
    evolve(24, n - BASE);
    evolve(39, n - BASE);
    putchar('\n');
    return 0;
}