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Last active Dec 25, 2015
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Edit Distance between strings in C.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
static inline unsigned int
min(unsigned int a, unsigned int b, unsigned int c)
unsigned int m = a;
if (m > b) m = b;
if (m > c) m = c;
return m;
int edit_distance(char *a, char *b) {
if (a[0] == '\0' && b[0] == '\0') // finished
return 0;
if (a[0] == '\0') // return the number of chars lesf in b
return strlen(b);
if (b[0] == '\0') // return the number of chars to remove from a
return strlen(a);
if (a[0] == b[0])
return edit_distance(a+1, b+1);
int distance_change = edit_distance(a+1, b+1) + 1;
int distance_addition = edit_distance(a, b+1) + 1;
int distance_deletion = edit_distance(a+1, b) + 1;
return min(distance_change, distance_addition, distance_deletion);
int main(int argc, char *argv[]) {
if (argc < 3)
return 0;
char *a = argv[1];
char *b = argv[2];
int distance = edit_distance(a, b);
printf("The distance between %s and %s is %d.\n", a, b, distance);
return 0;
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