EditStepInfo.java：
import lombok.Getter;
import lombok.Setter;
import java.io.Serializable;
import java.util.List;
@Getter
@Setter
public class EditStepInfo implements Serializable {
private String str1;
private String str2;
// str1和 str2 的最短编辑路基
private int sed;
private List<StepVO> steps;
}
StepVO.java：
import lombok.Getter;
import lombok.Setter;
import java.io.Serializable;
@Getter
@Setter
public class StepVO implements Serializable {
/**
* 当前变换描述
*/
private String desc;
private Character optChar1;
private Character optChar2;
/**
* 当前变换成的字符串
*/
private String tempString;
}
ShortestEditDistanceTest.java：
import java.util.ArrayList;
import java.util.List;
public class ShortestEditDistanceTest {
private static EditStepInfo[][] MAT_SED = null;
public static void main(String[] args) {
// m o t h e r
// m o n s t e r
String string1 = "mother";
String string2 = "monster";
MAT_SED = new EditStepInfo[ string1.length() ][ string2.length() ];
EditStepInfo editStepInfo = calculateShortestEditDistance(string1, string2);
System.out.println( string1 );
System.out.println( string2 );
System.out.println( "最小编辑距离：" + editStepInfo.getSed() );
System.out.println( "编辑步骤：" );
List<String> steps = editStepInfo.getSteps();
for( String step:steps ){
System.out.println( step );
}
}
private static EditStepInfo calculateShortestEditDistance( String string1,String string2 ){
if( string1 == null || string1.length() == 0 ){
EditStepInfo editStepInfo = new EditStepInfo();
editStepInfo.setStr1( string1 );
editStepInfo.setStr2( string2 );
editStepInfo.setSed( string2.length() );
return editStepInfo;
}
if( string2 == null || string2.length() == 0){
EditStepInfo editStepInfo = new EditStepInfo();
editStepInfo.setStr1( string1 );
editStepInfo.setStr2( string2 );
editStepInfo.setSed( string1.length() );
return editStepInfo;
}
int len1 = string1.length();
int len2 = string2.length();
for( int i=0;i<len1;i++ ){
String str1 = string1.substring(0, i + 1);
for( int j=0;j<len2;j++ ){
String str2 = string2.substring(0, j + 1);
EditStepInfo editStepInfo = new EditStepInfo();
editStepInfo.setStr1( str1 );
editStepInfo.setStr2( str2 );
if( str1.length() == 1 ){
if( str2.length() == 1 ){
if( str1.equals( str2 ) ){
// str1 和 str2 的长度均为1，并且 str1 和 str2 相等
// a
// a
editStepInfo.setSed( 0 );
}else {
// str1 和 str2 的长度均为1，并且 str1 和 str2 不相等
// a
// b
List<StepVO> steps = new ArrayList<>();
StepVO step = new StepVO();
step.setDesc( "将 " + str1 + " 修改为 " + str2 );
step.setTempString( str2 );
steps.add( step );
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}
}else {
if( str2.contains( str1 ) ){
// str1 的长度为1，str2 的长度大于1，并且 str1 在 str2 中不出现
// a
// ..a...
// 组装编辑步骤信息
List<StepVO> steps = buildEditSteps( str1.charAt(0),str2 );
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}else {
// str1 的长度为1，str2的长度大于1，并且str1在 str2中不存在
// a
// ..b...
// 组装编辑步骤信息
List<StepVO> steps = buildEditSteps(str1.charAt(0), str2);
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}
}
}else {
if( str2.length() == 1 ){
if( str1.contains( str2 ) ){
// ...a..
// a
// 组装编辑步骤信息
List<String> steps = buildEditSteps(str1, str2.charAt(0));
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}else {
// ...b..
// a
// 组装编辑步骤信息
List<String> steps = buildEditSteps(str1, str2.charAt(0));
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}
}else {
Character lastChar1 = getLastChar(str1);
Character lastChar2 = getLastChar(str2);
if( lastChar1.equals( lastChar2 ) ){
// ------a
// ---------a
// 组装编辑步骤信息
EditStepInfo editStepInfo_prev = MAT_SED[i - 1][j - 1];
List<String> steps = new ArrayList<>();
List<String> steps_prev = editStepInfo_prev.getSteps();
if( steps_prev != null ){
steps.addAll( steps_prev );
}
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}else {
// -----a
// ........b
// 1. str1 的 "-----" 部分转换为 str2，再删除 a
// 2. str1 转换为 str2 的 "........" 部分，再添加 b
// 3. str1 的 "-----" 部分转换为 str2 的 "........" 部分，再将a修改为 b
// 求 方法1、2、3中选一个最小的编辑步骤作为最终的编辑步骤
EditStepInfo editStepInfo_prev_1 = MAT_SED[i - 1][j];
EditStepInfo editStepInfo_prev_2 = MAT_SED[i][j - 1];
EditStepInfo editStepInfo_prev_3 = MAT_SED[i - 1][j - 1];
EditStepInfo editStepInfo_prev_min = editStepInfo_prev_1;
int minMethodNum = 1;
if( editStepInfo_prev_2.getSed() < editStepInfo_prev_min.getSed() ){
editStepInfo_prev_min = editStepInfo_prev_2;
minMethodNum = 2;
}
if( editStepInfo_prev_3.getSed() < editStepInfo_prev_min.getSed() ){
editStepInfo_prev_min = editStepInfo_prev_3;
minMethodNum = 3;
}
List<String> steps = new ArrayList<>();
List<String> steps_prev_min = editStepInfo_prev_min.getSteps();
if( steps_prev_min != null ){
steps.addAll( steps_prev_min );
}
if( minMethodNum == 1 ){
steps.add( "删除 " + lastChar1 );
}else if( minMethodNum == 2 ){
steps.add( "添加 " + lastChar2 );
}else if( minMethodNum == 3 ){
steps.add( "修改 " + lastChar1 + " 为 " + lastChar2 );
}
editStepInfo.setSteps( steps );
editStepInfo.setSed( steps.size() );
}
}
}
MAT_SED[ i ][ j ] = editStepInfo;
}
}
return MAT_SED[ string1.length() - 1 ][ string2.length() - 1 ];
}
/**
* 组装将字符 srcChar 转换成字符串 targetString 的编辑步骤
* @param srcChar 例如：a
* @param targetString 例如：bcdefg
* @return
*/
private static List<StepVO> buildEditSteps(Character srcChar, String targetString) {
boolean hasMeet = false;
int length = targetString.length();
List<StepVO> steps = new ArrayList<>();
for( int i = 0;i < length;i++ ){
Character char2 = targetString.charAt( i );
if( hasMeet ){
StepVO step = new StepVO();
step.setDesc( "添加 " + char2 );
step.setOptChar1( char2 );
steps.add( step );
}else {
if( srcChar.equals( char2 ) ){
// do nothing
hasMeet = true;
}else {
StepVO step = new StepVO();
step.setDesc( "添加 " + char2 );
step.setOptChar1( char2 );
steps.add( step );
}
}
}
if( !hasMeet ){
// 此种情况只发生在 targetString 中不包含 srcChar 时
StepVO step = new StepVO();
step.setDesc( "删除 " + srcChar );
step.setOptChar1( srcChar );
steps.add( 0,step );
}
// 设置 每个步骤生成的 tempString
String tempString = String.valueOf( srcChar );
for( StepVO step:steps ){
String desc = step.getDesc();
if( desc.startsWith( "删除" ) ){
tempString = "";
}else if( desc.startsWith( "添加" ) ){
tempString += step.getOptChar1();
}
step.setTempString( tempString );
}
return steps;
}
private static List<StepVO> buildEditSteps(String srcString, Character targetChar) {
// abcdefg
// c
boolean hasMeet = false;
int length = srcString.length();
List<StepVO> steps = new ArrayList<>();
for( int i = 0;i < length;i++ ){
Character char1 = srcString.charAt( i );
if( hasMeet ){
StepVO step = new StepVO();
step.setDesc( "删除 " + char1 );
step.setOptChar1( char1 );
steps.add( step );
}else {
if( targetChar.equals( char1 ) ){
// do nothing
hasMeet =true;
}else {
StepVO step = new StepVO();
step.setDesc( "删除 " + char1 );
step.setOptChar1( char1 );
steps.add( step );
}
}
}
if( !hasMeet ){
StepVO step = new StepVO();
step.setDesc( "添加 " + targetChar );
step.setOptChar1( targetChar );
steps.add( 0,step );
}
// todo 生成 tempString
String tempString = srcString;
for( StepVO step:steps ){
String desc = step.getDesc();
if( desc.startsWith( "添加" ) ){
}else if( desc.startsWith( "删除" ) ){
}
step.setTempString( null );
}
return steps;
}
private static Character getLastChar(String str) {
if( str == null || str.length() == 0 ){
return null;
}
return str.charAt(str.length() - 1);
}
}
mother
monster
最小编辑距离：3
编辑步骤：
添加 n
添加 s
删除 h
