LeetCode038 Count and Say

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详细见：leetcode.com/problems/count-and-say

Java Solution: github

package leetcode;public class P038_CountAndSay {/* * 2 ms * 85.40% */static class Solution {public String countAndSay(int n) {if (n < 1) {return null;}String result = "1";for (int i = 2; i <= n; i++) {result = countAndSay(result);}return result;}public String countAndSay(String str) {StringBuilder builder = new StringBuilder(128);int count = 1;for (int i = 1; i < str.length(); i++) {if (str.charAt(i) == str.charAt(i - 1)) {count++;} else {builder.append(count);builder.append(str.charAt(i - 1));count = 1;}}builder.append(count);builder.append(str.charAt(str.length() - 1));return builder.toString();}}}

C Solution: github

/*    url: leetcode.com/problems/count-and-say/    3ms 15.29%*/#include <stdlib.h>#include <stdio.h>#include <string.h>//array list starttypedef char T;typedef struct al sal;typedef struct al * pal;struct al {    int capacity;    int size;    T* arr;};void al_expand_capacity(pal l) {    T* new_arr = (T*) malloc(sizeof(T) * (l->capacity * 2 + 1));    int i = 0;    for (i = 0; i < l->capacity; i ++)        new_arr[i] = l->arr[i];    free(l->arr);    l->arr = new_arr;    l->capacity = l->capacity * 2 + 1;}void al_add_last(pal l, T v) {    if (l->capacity == l->size) al_expand_capacity(l);    l->arr[l->size] = v;    l->size ++;}void al_add_first(pal l, T v) {    int i = 0;    if (l->capacity == l->size) al_expand_capacity(l);    for (i = l->size; i > 0; i --)        l->arr[i] = l->arr[i - 1];    l->arr[0] = v;    l->size ++;}void al_add_to_index(pal l, T v, int index) {    int i = 0;    if (index < 0 || index > l->size) return;    if (l->capacity == l->size) al_expand_capacity(l);    for (i = l->size - 1; i >= index; i --) {        l->arr[i+1] = l->arr[i];    }    l->arr[index] = v;    l->size ++;}void al_set_index(pal l, T v, int index) {    if (index < 0 || index > l->size) return;    if (index == l->size) {        al_add_last(l, v);        return;    }    l->arr[index] = v;    //if T by malloc, need to free}//if T is ptr, need to free l->size - 1void al_remove_last(pal l) {    if (l->size == 0) return;    l->arr[l->size - 1] = 0; //or NULL and free    l->size --;}//if T is ptr, need to free 0void al_remove_first(pal l) {    int i = 0;    if (l->size == 0) return;    l->arr[0] = 0; //or NULL and free    for (i = 1; i < l->size; i ++) {        l->arr[i - 1] = l->arr[i];    }    l->size --;}T* al_convert_to_array_free_l(pal l) {    T* arr = l->arr;    free(l);    return arr;}T al_val(pal l, int index) {    if (index >= l->size || index < 0) return 0;    return l->arr[index];}void al_free_all(pal l) {    free(l->arr);    free(l);}void al_print(pal l) {    int i = 0;    if (l->size == 0) return;    for (i = 0; i < l->size; i ++)        printf("%d ", l->arr[i]);    printf("\r\n");}//array list endvoid itoa_my(int val, char* chs, int radix) {    int ATOA_MY_LEN = 33;    char s[33];    int index = ATOA_MY_LEN;    int negative = val < 0;    //invalid radix    if (radix < 2) return;    s[-- index] = '\0';    while (val != 0) {        s[-- index] = (char)(abs(val % radix) + '0');        val = val / radix;    }    if (negative) {        s[-- index] = '-';    }    //reuse negative as chs index    negative = 0;    while (index < ATOA_MY_LEN) {        *(chs + negative ++) = s[index ++];    }}char* check_cap(char* to_check, int* to_check_cap, int to_check_index) {    int new_cap = 0, index = 0;    char* temp = NULL;    if (to_check_index < *to_check_cap) return to_check;    new_cap = to_check_index + 100 > 2 * *to_check_cap ? to_check_index + 100 : 2 * *to_check_cap;    temp = (char*) malloc(sizeof(char) * (new_cap + 1));    for (index = 0; index <= *to_check_cap; index ++) {        *(temp + index) = *(to_check + index);    }    *to_check_cap = new_cap;    free(to_check);    return temp;}void swap_pchar(char** a, char** b) {    char* t = * a;    *a = *b;    *b = t;}void swap_int(int* a, int *b) {    int t = *a;    *a = *b;    *b = t;}void swap_al(pal* a, pal* b) {    pal t = *a;    *a = *b;    *b = t;}char* countAndSay(int n) {    int answer_cap = 1, save_cap = 1, ni = 1;    int answer_size = 0, save_size = 0;    int answer_index = 0, save_index = 0, char_count = 0;    int int_char_index = 0;    char int_char[14];    char char_pre = '\0';    pal answer = (pal) malloc(sizeof(sal));    pal save = (pal) malloc(sizeof(sal));    char* temp = NULL;    answer->capacity = 16;    answer->size = 0;    answer->arr = (T*) malloc(sizeof(T) * answer->capacity);    save->capacity = 16;    save->size = 0;    save->arr = (T*) malloc(sizeof(T) * save->capacity);    al_add_last(answer, '1');        while (n != ni) {        //just count        ni ++;        //count answer to save        char_pre = '\0';        char_count = 0;        save_index = 0;        answer_index = 0;        save->size = 0;        while (answer_index <= answer->size) {            //only char_count ++ and continue            if (answer_index != answer->size && al_val(answer, answer_index) == char_pre) {                char_count ++;                answer_index ++;                continue;            }            if (answer_index != 0) {                //save to save                itoa_my(char_count, int_char, 10);                int_char_index = 0;                while (int_char[int_char_index] != '\0') {                    al_add_last(save, int_char[int_char_index ++]);                }                al_add_last(save, char_pre);            }            if (answer_index != answer->size) {                char_count = 1;                char_pre = al_val(answer, answer_index ++);            } else break;        }        swap_al(&answer, &save);          }    al_free_all(save);    al_add_last(answer, '\0');    return al_convert_to_array_free_l(answer);}int main() {    int n = 15;    char* ans = countAndSay(n);    printf("answer is %s\r\n", ans);    free(ans);}

Python Solution: github

#coding=utf-8'''    url: leetcode.com/problems/count-and-say/    @author:     zxwtry    @email:      zxwtry@qq.com    @date:       2017年4月5日    @details:    Solution: 72ms 13.30%'''class Solution(object):    def countAndSay(self, n):        """        :type n: int        :rtype: str        """        if n < 1: return ""        if n == 1: return "1"        answer="1"        for i in range(n-1):            record, pre_char, pre_count=[], "ddd", 0            for j in range(len(answer)):                if answer[j] == pre_char:                    pre_count += 1                else:                    if pre_count != 0:                        record.append(str(pre_count))                        record.append(pre_char)                    pre_char = answer[j]                    pre_count = 1            if pre_count != 0:                record.append(str(pre_count))                record.append(pre_char)            answer = "".join(record)        return answerif __name__ == "__main__":    print(Solution().countAndSay(4))

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