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package com.sun.enterprise.admin.cli;
public class StringEditDistance {
/**
* Computes the edit distance between two strings.
*
*
* The complexity is O(nm) where n=a.length() and m=b.length().
*/
public static int editDistance(String a, String b) {
return new StringEditDistance(a, b).calc();
}
/**
* Finds the string in the group closest to
* key and returns it.
*
* @return null if group.length==0.
*/
public static String findNearest(String key, String[] group) {
int c = Integer.MAX_VALUE;
String r = null;
for (int i = 0; i < group.length; i++) {
int ed = editDistance(key, group[i]);
if (c > ed) {
c = ed;
r = group[i];
}
}
return r;
}
/** cost vector. */
private int[] cost;
/** back buffer. */
private int[] back;
/** Two strings to be compared. */
private final String a,b;
private StringEditDistance(String a, String b) {
this.a = a;
this.b = b;
cost = new int[a.length() + 1];
back = new int[a.length() + 1];
// back buffer
for (int i = 0; i <= a.length(); i++)
cost[i] = i;
}
/**
* Swaps two buffers.
*/
private void flip() {
int[] t = cost;
cost = back;
back = t;
}
private int min(int a, int b, int c) {
return Math.min(a, Math.min(b, c));
}
private int calc() {
for (int j = 0; j < b.length(); j++) {
flip();
cost[0] = j + 1;
for (int i = 0; i < a.length(); i++) {
int match = (a.charAt(i) == b.charAt(j)) ? 0 : 1;
cost[i+1] = min(back[i] + match, cost[i] + 1, back[i+1] + 1);
}
}
return cost[a.length()];
}
}