题解 | #单词倒排#

#include <stdio.h>
#include <string.h>

#define MAX 10001

void delete_char(char *s, int i) {
    if (s == NULL || i < 0 || i >= strlen(s)) {
        return;
    }
    int len = strlen(s);
    for (int j = i; j < len - 1; j++) {
        s[j] = s[j+1];
    }
    s[len-1] = '\0';
}

void reverse_s(char *start, char *end){
    char m;
    for(int i = 0; start + i < end - i; i++){
        m = *(end - i);
        *(end - i) = *(start + i);
        *(start + i) = m;
    }
}


int main(){

    char arr[MAX];
/*
    scanf("%s", arr);
    int len = strlen(arr) - 1;
*/
    fgets(arr, sizeof(arr), stdin);
    arr[strlen(arr) - 1] = '\0';
    int len = strlen(arr);
    for(int i = 0; i < len; i++){
        if((arr[i] >= 'a') && (arr[i] <= 'z')){}

        else if((arr[i] >= 'A') && (arr[i] <= 'Z')){}

        else{
            if(arr[i - 1] == ' ')
                delete_char(arr, i);
            else
                arr[i] = ' ';
        }
    } 
    len = strlen(arr);
    char *start = arr;
    for(int i = 0; i <= len; i++){
        if((arr[i] == ' ') || (arr[i] == '\0')){
            reverse_s(start, arr + i - 1);
            start = arr + i + 1;
        }
    }
    reverse_s(arr, arr + len - 1);
    printf("%s", arr);

    return 0;
}