算法_动态规划_电路布线

import java.util.Scanner;


public class Main {
    private static int n;
    private static int[][] size;
    private static int[] pi;

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        init();
        dp();
        System.out.println(size[n-1][n-1]);
        traceBack();
    }

    private static void init(){
        Scanner sc=new Scanner(System.in);
        n=sc.nextInt();
        pi=new int[n];
        size=new int[n][n];
        for(int i=0;i<n;i++){
            pi[i]=sc.nextInt();
        }
    }
    private static void dp(){
        for(int j=0;j<n;j++){
            if(j<pi[0]){
                size[0][j]=0;
            }else{
                size[0][j]=1;
            }
        }
        for(int i=1;i<n;i++){
            for(int j=0;j<n;j++){
                if(j<pi[i]){
                    size[i][j]=size[i-1][j];
                }else{
                    if(pi[i]==0){
                        size[i][j]=Math.max(size[i-1][j],1);
                    }else{
                        size[i][j]=Math.max(size[i-1][j],size[i-1][pi[i]-1]+1);
                    }

                }
            }
        }
    }

    private static void traceBack(){
        int j=n-1;
        for(int i=n-1;i>0;i--){
            if(size[i][j]!=size[i-1][j]){
                System.out.print(i+" ");
                j=pi[i]-1;
            }
        }
        if(j>=pi[0]){
            System.out.println(0);
        }

    }

}