hihoCoder #1197 Give My Text Back

Description

To prepare for the English exam Little Ho collected many digital reading materials. Unfortunately the materials are messed up by a malware.

It is known that the original text contains only English letters (a-zA-Z), spaces, commas, periods and newlines, conforming to the following format:

1. Each sentence contains at least one word, begins with a letter and ends with a period.

2. In a sentence the only capitalized letter is the first letter.

3. In a sentence the words are separated by a single space or a comma and a space.

4. The sentences are separated by a single space or a single newline.

It is also known the malware changes the text in the following ways:

1. Changing the cases of letters.

2. Adding spaces between words and punctuations.

Given the messed text, can you help Little Ho restore the original text?

Input

A string containing no more than 8192 English letters (a-zA-Z), spaces, commas, periods and newlines which is the messed text.

Output

The original text.

Sample Input

my Name  is Little   Hi.
His   name IS Little ho  ,  We are   friends.

Sample Output

My name is little hi.
His name is little ho, we are friends.

Solution:

#include <cstdio>
#include <cstring>
#define MAXN 10000

char toUpper(char c) {
    if (c >= 'A' && c <= 'Z') return c;
    else return 'A' + (c - 'a');
}

char toLower(char c) {
    if (c >= 'a' && c <= 'z') return c;
    else return 'a' + (c - 'A');
}

int main() {
    char buf[MAXN];
    char text[MAXN];
    while (fgets(buf, MAXN, stdin)) {
        //printf("%s\n", buf);
        int len = strlen(buf);
        int idx = -1;
        int k = 0;
        int flag = true;
        for (int i = 0; i < len; ++i) {
            
            if ((buf[i] >= 'a' && buf[i] <= 'z') || buf[i] >= 'A' && buf[i] <= 'Z') {
                if (idx >= 0) {
                    k = idx + 1;
                    idx = -1;
                }
                if (flag) {
                    text[k++] = toUpper(buf[i]);
                    flag = false;
                }
                else 
                    text[k++] = toLower(buf[i]);
            }
            else if (buf[i] == ' ') {
                if (idx < 0) {
                    idx = k;
                }
                text[k++] = buf[i];
            }
            else if (buf[i] == ',') {
                if (idx >= 0) {
                    k = idx;
                    idx = -1;
                }
                text[k++] = buf[i];
            }
            else if (buf[i] == '.') {
                if (idx >= 0) {
                    k = idx;
                    idx = -1;
                }
                text[k++] = buf[i];
                flag = true;
            }
            else text[k++] = buf[i];
            
        }
        text[k] = '\0';
        printf("%s", text);
    }

}