Task: Word wrap

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>


const char *string = "In olden times when wishing still helped one, there lived a king "
    "whose daughters were all beautiful, but the youngest was so beautiful "
    "that the sun itself, which has seen so much, was astonished whenever "
    "it shone-in-her-face.  Close-by-the-king's castle lay a great dark "
    "forest, and under an old lime-tree in the forest was a well, and when "
    "the day was very warm, the king's child went out into the forest and "
    "sat down by the side of the cool-fountain, and when she was bored she "
    "took a golden ball, and threw it up on high and caught it, and this "
    "ball was her favorite plaything.";



#define PENALTY_LONG    100
#define PENALTY_SHORT   1

typedef struct word_t {
    const char *s;
    int len;
} *word;

word make_word_list(const char *s, int *n)
{
    int max_n = 0;
    word words = 0;

    *n = 0;
    while (1) {
        while (*s && isspace(*s)) s++;
        if (!*s) break;

        if (*n >= max_n) {
            if (!(max_n *= 2)) max_n = 2;
            words = realloc(words, max_n * sizeof(*words));
        }
        words[*n].s = s;
        while (*s && !isspace(*s)) s++;
        words[*n].len = s - words[*n].s;
        (*n) ++;
    }

    return words;
}

int greedy_wrap(word words, int count, int cols, int *breaks)
{
    int score = 0, line, i, j, d;

    i = j = line = 0;
    while (1) {
        if (i == count) {
            breaks[j++] = i;
            break;
        }

        if (!line) {
            line = words[i++].len;
            continue;
        }

        if (line + words[i].len < cols) {
            line += words[i++].len + 1;
            continue;
        }

        breaks[j++] = i;
        if (i < count) {
            d = cols - line;
            if (d > 0)  score += PENALTY_SHORT * d * d;
            else if (d < 0) score += PENALTY_LONG * d * d;
        }

        line = 0;
    }
    breaks[j++] = 0;

    return score;
}


int balanced_wrap(word words, int count, int cols, int *breaks)
{
    int *best = malloc(sizeof(int) * (count + 1));

    
    int best_score = greedy_wrap(words, count, cols, breaks);

    void test_wrap(int line_no, int start, int score) {
        int line = 0, current_score = -1, d;

        while (start <= count) {
            if (line) line ++;
            line += words[start++].len;
            d = cols - line;
            if (start < count || d < 0) {
                if (d > 0)
                    current_score = score + PENALTY_SHORT * d * d;
                else
                    current_score = score + PENALTY_LONG * d * d;
            } else {
                current_score = score;
            }

            if (current_score >= best_score) {
                if (d <= 0) return;
                continue;
            }

            best[line_no] = start;
            test_wrap(line_no + 1, start, current_score);
        }
        if (current_score >= 0 && current_score < best_score) {
            best_score = current_score;
            memcpy(breaks, best, sizeof(int) * (line_no));
        }
    }
    test_wrap(0, 0, 0);
    free(best);

    return best_score;
}

void show_wrap(word list, int count, int *breaks)
{
    int i, j;
    for (i = j = 0; i < count && breaks[i]; i++) {
        while (j < breaks[i]) {
            printf("%.*s", list[j].len, list[j].s);
            if (j < breaks[i] - 1)
                putchar(' ');
            j++;
        }
        if (breaks[i]) putchar('\n');
    }
}

int main(void)
{
    int len, score, cols;
    word list = make_word_list(string, &len);
    int *breaks = malloc(sizeof(int) * (len + 1));

    cols = 80;
    score = greedy_wrap(list, len, cols, breaks);
    printf("\n== greedy wrap at %d (score %d) ==\n\n", cols, score);
    show_wrap(list, len, breaks);

    score = balanced_wrap(list, len, cols, breaks);
    printf("\n== balanced wrap at %d (score %d) ==\n\n", cols, score);
    show_wrap(list, len, breaks);


    cols = 32;
    score = greedy_wrap(list, len, cols, breaks);
    printf("\n== greedy wrap at %d (score %d) ==\n\n", cols, score);
    show_wrap(list, len, breaks);

    score = balanced_wrap(list, len, cols, breaks);
    printf("\n== balanced wrap at %d (score %d) ==\n\n", cols, score);
    show_wrap(list, len, breaks);

    return 0;
}







Python: >>> import textwrap
>>> help(textwrap.fill)
Help on function fill in module textwrap:

fill(text, width=70, **kwargs)
    Fill a single paragraph of text, returning a new string.
    
    Reformat the single paragraph in 'text' to fit in lines of no more
    than 'width' columns, and return a new string containing the entire
    wrapped paragraph.  As with wrap(), tabs are expanded and other
    whitespace characters converted to space.  See TextWrapper class for
    available keyword args to customize wrapping behaviour.

>>> txt = 
>>> print(textwrap.fill(txt, width=75))
Reformat the single paragraph in 'text' to fit in lines of no more than
'width' columns, and return a new string containing the entire wrapped
paragraph.  As with wrap(), tabs are expanded and other whitespace
characters converted to space.  See TextWrapper class for available keyword
args to customize wrapping behaviour.
>>> print(textwrap.fill(txt, width=45))
Reformat the single paragraph in 'text' to
fit in lines of no more than 'width' columns,
and return a new string containing the entire
wrapped paragraph.  As with wrap(), tabs are
expanded and other whitespace characters
converted to space.  See TextWrapper class
for available keyword args to customize
wrapping behaviour.
>>> print(textwrap.fill(txt, width=85))
Reformat the single paragraph in 'text' to fit in lines of no more than 'width'
columns, and return a new string containing the entire wrapped paragraph.  As with
wrap(), tabs are expanded and other whitespace characters converted to space.  See
TextWrapper class for available keyword args to customize wrapping behaviour.
>>>