Rm/add word distance

dp/README.md

@@ -44,3 +44,7 @@ Given an array representing the amount of wealth inside houses like `{1,2,3,4}`
 ### Minimum Deletion to Make a Palindrome
 
 Given a string like `abccb` return the minimum number of character deletions that can be done on the string to make it a palindrome like `1` (by removing `a`, we will have `bccb`). [Solution](minimum_deletion_to_make_palindrome.go), [Tests](minimum_deletion_to_make_palindrome_test.go)
+
+### Word Distance
+
+Given a string like `abc`, and another string like `abcde` return how many character modifications (insert, delete, edit) have to be done on the first string to become identical to the second string. [Solution](word_distance.go.go), [Tests](word_distance.go_test.go)

dp/minimum_deletion_to_make_palindrome.go

@@ -1,5 +1,7 @@
 package dp
 
+// MinimumDeletionsToMakePalindrome returns how many deletions can be done in the input string
+// to make it a palindrome.
 func MinimumDeletionsToMakePalindrome(input string) int {
 	if len(input) <= 1 {
 		return 0

dp/word_distance.go

@@ -0,0 +1,45 @@
+package dp
+
+// WordDistance returns how many character modifications (insert, delete, edit) can
+// be done on the first input string so that it becomes equal to the second string.
+func WordDistance(input1, input2 string) int {
+	dp := createDP(input2, input1)
+	for i := 1; i <= len(input1); i++ {
+		for j := 1; j <= len(input2); j++ {
+			if input1[i-1] == input2[j-1] {
+				dp[i][j] = dp[i-1][j-1]
+			} else {
+				dp[i][j] = 1 + min(
+					dp[i-1][j], // delete
+					min(dp[i][j-1], // insert
+						dp[i-1][j-1])) // edit
+			}
+		}
+	}
+	return dp[len(input1)][len(input2)]
+}
+
+func createDP(input2 string, input1 string) [][]int {
+	dp := make([][]int, len(input1)+1)
+
+	for i := range dp {
+		dp[i] = make([]int, len(input2)+1)
+	}
+
+	for i := 0; i <= len(input1); i++ {
+		dp[i][0] = i
+	}
+
+	for j := 0; j <= len(input2); j++ {
+		dp[0][j] = j
+	}
+
+	return dp
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}

dp/word_distance_test.go

@@ -0,0 +1,29 @@
+package dp
+
+import (
+	"testing"
+)
+
+func TestWordDistance(t *testing.T) {
+	tests := []struct {
+		input1   string
+		input2   string
+		distance int
+	}{
+		{"", "", 0},
+		{"", "abcde", 5},
+		{"a", "a", 0},
+		{"a", "b", 1},
+		{"ab", "ac", 1},
+		{"ab", "dc", 2},
+		{"ab", "dcd", 3},
+		{"abcdef", "abcde", 1},
+		{"gabcdef", "abcde", 2},
+	}
+
+	for i, test := range tests {
+		if got := WordDistance(test.input1, test.input2); got != test.distance {
+			t.Fatalf("Failed test case #%d. Want %d got %d", i, test.distance, got)
+		}
+	}
+}