使用递归反转单词 [英] reverse a word using recursion

问题描述

我正在尝试使用 c 中的递归来反转一个单词，然后我做到了.

I am trying to reverse a word using recursion in c and i got upto this.

#include<stdio.h>

void reverse(char *a){
    if(*a){
        reverse(a+1);
        printf("%c",*a);
    }
}

int main() {
    char a[] = "i like this program very much";
    reverse(a); // i ekil siht margorp yrev 
    return 0;
}

假设输入的字符串是我非常喜欢这个程序.该函数应该将字符串更改为 非常像 i

Suppose the input string is i like this program very much. The function should change the string to much very program this like i

Algorithm:

1) Reverse the individual words, we get the below string.
     "i ekil siht margorp yrev hcum"
2) Reverse the whole string from start to end and you get the desired output.
     "much very program this like i"

我已经成功完成了第 1 步，但我不确定如何进一步进行.请帮忙.

I have successfully completed up-to step 1 and i am not sure how to proceed further. Please help.

推荐答案

#include <stdio.h>
#include <ctype.h>

void swap(char *a, char *b){
    char wk = *a;
    *a = *b;
    *b = wk;
}

void strpartrev(char *top, char *tail){
    while(top < tail)
        swap(top++, tail--);
}

void step1(char *a){
    while(isspace(*a))
        ++a;
    if(!*a)
        return;
    char *top =a;
    while(a[1] && !isspace(a[1]))
        ++a;
    char *tail = a;
    strpartrev(top, tail);
    step1(a+1);
}

int step2(char *str, int pos){
    char ch = str[pos];
    return (ch == '\0')? 0 : ((str[pos=step2(str, ++pos)]=ch), ++pos);
}

void reverse(char *a){
    step1(a);
    step2(a, 0);
}

int main() {
    char a[] = "i like this program very much";
    reverse(a);
    puts(a);//much very program this like i
    return 0;
}

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