# Problem D - Zipf's Law

Problem D - Zipf's Law

### Problem D - Zipf's Law

Harvard linguistics professor George Kingsley Zipf (1902-1950) observed that the frequency of the kth most common word in a text is roughly proportional to 1/k. He justified his observations in a book titled Human behavior and the principle of least effort published in 1949. While Zipf's rationale has largely been discredited, the principle still holds, and others have afforded it a more sound mathematical basis. Input consists of several test cases. The first line of each case contains a single positive integer n. Several lines of text follow which will contain no more than 10000 words. The text for each case is terminated by a single line containing EndOfText. EndOfText does not appear elsewhere in the input and is not considered a word.

For each test case, output the words which occur n times in the input text, one word per line, lower case, in alphabetical order. If there are no such words in input, output the following line:

```There is no such word.
```

Leave a blank line between cases.

``````2

In practice, the difference between theory and practice is always
greater than the difference between theory and practice in theory.
- Anonymous

Man will occasionally stumble over the truth, but most of the
time he will pick himself up and continue on.
- W. S. L. Churchill
EndOfText``````

``````between
difference
in
will``````

``````#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

int c,i,j,k,n,wn;

char w, buf;

int main(){

while (1 == scanf("%d",&n)) {
if (c++) printf("\n");
wn = 0;
for (;;) {
if (1 != scanf("%[^a-zA-Z]",buf)) break;
if (1 != scanf("%[a-zA-Z]",buf)) break;
if (!strcmp(buf,"EndOfText")) break;
for (i=0;buf[i];i++) buf[i] = tolower(buf[i]);
strcpy(w[wn++],buf);
}
qsort(w,wn,100,strcmp);
strcpy(w[wn++],"***");
strcpy(buf,"\$\$\$");
for (i=j=0;i<wn;i++) {
if (strcmp(buf,w[i])) {
if (strcmp(buf,"\$\$\$") && k == n) printf("%s\n",buf),j=1;
strcpy(buf,w[i]);
k = 0;
}
k++;
}
if (!j) printf("There is no such word.\n");
}
}``````

``````#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

int c,i,j,k,n,wn;

char w, buf;

int main(){

while (1 == scanf("%d",&n)) {
if (c++) printf("\n");
wn = 0;
for (;;) {
if (1 != scanf("%[^a-zA-Z]",buf)) break;
if (1 != scanf("%[a-zA-Z]",buf)) break;
if (!strcmp(buf,"EndOfText")) break;
for (i=0;buf[i];i++) buf[i] = tolower(buf[i]);
strcpy(w[wn++],buf);
}
qsort(w,wn,100,strcmp);
strcpy(w[wn++],"***");
strcpy(buf,"\$\$\$");
for (i=j=0;i<wn;i++) {
if (strcmp(buf,w[i])) {
if (strcmp(buf,"\$\$\$") && k == n) printf("%s\n",buf),j=1;
strcpy(buf,w[i]);
k = 0;
}
k++;
}
if (!j) printf("There is no such word.\n");
}
}``````