编程算法之动态规划之最长公共子序列（java版）

问题：给定的两串字符，要求变成求出最长公共子序列；

程序：

import java.util.Scanner;

public class LCS {

/**

* @param args

*/

public static void main(String[] args) { //可以实现用户自己输入两串字符：

// TODO Auto-generated method stub

Scanner scanner = new Scanner(System.in);

System.out.println("请输入一串字符：");

String s1 = scanner.next();

System.out.println("请输入一串字符：");

String s2 = scanner.next();

int c[][] = new int [s1.length() + 1][s2.length() + 1];

int b[][] = new int [s1.length() + 1][s2.length() + 1];

sort(s1,s2,c,b);

}

public static void sort(String s1,String s2,int c[][],int b[][]) { //该方法实现统计

int n = s1.length();

int m = s2.length();

char array1[] = s1.toCharArray();

char array2[] = s2.toCharArray();

for(int i = 1; i <= n; i++) {

c[i][0] = 0;

}

for(int j = 1; j <= m; j++) {

c[0][j] = 0;

}

for(int i = 1; i <= n; i++) {

for(int j = 1 ; j <= m; j++ ) {

if(array1[i-1] == array2[j-1]) {

c[i][j] = c[i-1][j-1] + 1;

b[i][j] = 1;

}

else if(c[i-1][j] >= c[i][j-1]) {

c[i][j] = c[i-1][j];

b[i][j] = 2;

}

else {

c[i][j] = c[i][j-1];

b[i][j] =3;

}

}

}

System.out.println("最长子序列为：");

print_sort(n, m, array1, b);

}

public static void print_sort(int n,int m,char ch [],int b[][]) { //该方法根据统计函数所得结果实现

//输出

if(n == 0 || m ==0) return;

if(b
[m] == 1) {

print_sort(n-1, m-1, ch, b);

System.out.print(ch[n-1]);

}

else if(b
[m] == 2) {

print_sort(n-1, m, ch, b);

}

else

print_sort(n, m -1, ch, b);

}

}