import java.util.Scanner;
//最长公共子序列
public class LCS {
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
char[] x;
char[] y;
String stringX=scanner.nextLine();
x=stringX.toCharArray();
String stringY=scanner.nextLine();
y=stringY.toCharArray();
//c[i][j]记录Xi和Yj的最长公共子序列长度
int[][] c=new int[x.length+1][y.length+1];
//b[i][j]记录c[i][j]的值是由哪个子问题解到的
int[][] b=new int[x.length+1][y.length+1];
LCSLength(x, y, x.length, y.length, b,c);
System.out.println(c[x.length][y.length]);
printLCS(x.length, y.length, x, b);
}
private static void LCSLength(char[] x,char[]y,int m,int n,int[][] b,int[][]c){
int i,j;
for (i = 1; i <= m; i++) {
c[i][0]=0;
}
for (j = 1; j <= n; j++) {
c[0][j]=0;
}
for (i = 1; i <= m; i++) {
for (j = 1; j <= n; j++) {
if (x[i-1]==y[j-1]) {
c[i][j]=1+c[i-1][j-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;
}
}
}
}
//打印最长子序列
private static void printLCS(int i,int j,char[] x,int[][] b){
if (i==0||j==0) return;
if (b[i][j]==1) {
printLCS(i-1, j-1, x, b);
System.out.print(x[i-1]);
}
else if (b[i][j]==2) {
printLCS(i-1, j, x, b);
}
else {
printLCS(i, j-1, x, b);
}
}
}
动态规划:最长公共子序列
最新推荐文章于 2024-04-29 21:11:51 发布