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-rw-r--r--edit_distance.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/edit_distance.c b/edit_distance.c
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+++ b/edit_distance.c
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+// 72. Edit Distance
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MIN(a, b, c) \
+ ((a) < (b) ? ((a) < (c) ? (a) : (c)) : ((b) < (c) ? (b) : (c)))
+
+/*
+ * given two strings 'word1' and 'word2', return minimum number of operations
+ * required to convert 'word1' to 'word2'. the following operations are
+ * permitted: insert character, delete character, replace character
+ */
+
+int minDistance(char *word1, char *word2) {
+ int len1 = strlen(word1), len2 = strlen(word2);
+ if (len1 == 0)
+ return len2;
+ if (len2 == 0)
+ return len1;
+ int **table = (int **)malloc(len1 * sizeof(int *));
+ for (int i = 0; i < len1; i++)
+ table[i] = (int *)malloc(len2 * sizeof(int));
+ if (word1[0] == word2[0])
+ table[0][0] = 0;
+ else
+ table[0][0] = 1;
+ for (int i = 1; i < len2; i++) {
+ if (word1[0] == word2[i])
+ table[0][i] = i;
+ else
+ table[0][i] = table[0][i - 1] + 1;
+ }
+ for (int i = 1; i < len1; i++) {
+ if (word2[0] == word1[i])
+ table[i][0] = i;
+ else
+ table[i][0] = table[i - 1][0] + 1;
+ }
+ for (int i = 1; i < len1; i++)
+ for (int j = 1; j < len2; j++) {
+ if (word1[i] == word2[i])
+ table[i][j] = table[i - 1][j - 1];
+ else
+ table[i][j] =
+ MIN(table[i - 1][j], table[i][j - 1], table[i - 1][j - 1]);
+ }
+ int ans = table[len1 - 1][len2 - 1];
+ for (int i = 0; i < len1; i++)
+ free(table[i]);
+ free(table);
+ return ans;
+}
+
+int main() {
+ char w11[] = "horse", w21[] = "ros";
+ char w12[] = "intention", w22[] = "execution";
+ printf("%d\n", minDistance(w11, w21)); // expect: 3
+ printf("%d\n", minDistance(w12, w22)); // expect: 5
+}