Java最长公共子序列示例源码

package com.wsy.dynamic;
import java.util.HashMap;
import java.util.Map;
public class ImpLCS {
 public String getLCS(String str1, String str2, int n, int m){
  validate(str1, str2);
  char[] a = str1.toCharArray();
  char[] b = str2.toCharArray();
  int[][] c = new int[n+1][m+1];
  //存放序列
  Map<String,String> map = new HashMap<String,String>();
  //初始化参数
  for(int i = 0;i<=n;i++){
   c[i][0] = 0;
   map.put(i + "0", "");
  }
  for(int i = 0;i<=m;i++){
   c[0][m] = 0;
   map.put("0" + i, "");
  }
  for(int i = 1;i<=n;i++){
   for(int j = 1;j<=m;j++){
    if(a[i-1] == b[j-1]){
     c[i][j] = c[i-1][j-1] + 1;
     String tmp = map.get(changeNum(i-1,j-1));
     map.put(changeNum(i,j), tmp + String.valueOf(a[i-1]));
    }else{
     if(c[i][j-1] > c[i-1][j]){
      c[i][j] = c[i][j-1];
      String tmp = map.get(changeNum(i,j-1));
      map.put(changeNum(i,j), tmp);
     }else{
      c[i][j] = c[i-1][j];
      String tmp = map.get(changeNum(i-1,j));
      map.put(changeNum(i,j), tmp);
     }
    }
   }
  }
  String key = changeNum(n,m);
  return map.get(key);
 }
 /**
  * 将数字拼接成字符串
  * @param i
  * @param j
  * @return
  */
 private String changeNum(int i, int j) {
  StringBuilder sb = new StringBuilder(String.valueOf(i));
  return sb.append(j).toString();
 }
 /**
  * 验证参数
  * @param str1
  * @param str2
  */
 private void validate(String str1, String str2) {
  // 略
 }
 public static void main(String[] args) {
  ImpLCS lcs = new ImpLCS();
  String rs = lcs.getLCS("12345", "12334", 5, 4);
  System.out.println("---:" + rs);
 }
}