reorg and add code for second edition

11_dynamic_programming/javascript/02_levenstein.js

@@ -0,0 +1,47 @@
+/**
+ * Compute the edit distance between the two given strings
+ *
+ * @param {*} source
+ * @param {*} target
+ *
+ * @return {number}
+ */
+function getEditDistance(source, target) {
+	if (source.length == 0) return target.length;
+	if (target.length == 0) return source.length;
+
+	let i;
+	let j;
+	let matrix = [];
+
+	// Fill the column
+	for (i = 0; i <= target.length; i++) {
+		matrix[i] = [i];
+	}
+
+	// Fill the column
+	for (j = 0; j <= source.length; j++) {
+		matrix[0][j] = j;
+	}
+
+	// Fill in the rest of the matrix
+	for (i = 1; i <= target.length; i++) {
+		for (j = 1; j <= source.length; j++) {
+			if (target.charAt(i - 1) == source.charAt(j - 1)) {
+				matrix[i][j] = matrix[i - 1][j - 1];
+			} else {
+				matrix[i][j] = Math.min(
+					matrix[i - 1][j - 1] + 1, // substitution
+					Math.min(
+						matrix[i][j - 1] + 1, // insertion
+						matrix[i - 1][j] + 1
+					)
+				); // deletion
+			}
+		}
+	}
+
+	return matrix[target.length][source.length];
+}
+
+console.log(getEditDistance("google", "notgoogl")); // 4