#include <cstdio>
#include <cstring>

void reverse(char * str, int size) {
    for(int i = 0; i < size / 2; ++i) {
        char c = str[i];
        str[i] = str[size - i - 1];
        str[size - i - 1] = c;
    }
}

char * reverse_words(char * str) {
    reverse(str, strlen(str));
    char * p = str;
    char * ps = str;

    while(*p) {
        if(*p == ' ' || *p == '\0') {
            reverse(ps, int(p - ps));
            ps = p + 1;
        }
        p++;
    }
    reverse(ps, int(p - ps));
    return str;
}

int main() {
    char * words = new char[128];
    strcpy(words, "tests while notebook");
    printf("%s\n", reverse_words((char *)words));
    return 0;
}