Submission #291147

# Submission time Handle Problem Language Result Execution time Memory
291147 2020-09-04T19:17:23 Z Agnimandur Sailing Race (CEOI12_race) Java 11
Compilation error
0 ms 0 KB
import java.io.*;
import java.util.*;

public class Main {
    static final long MOD = 1000000007L;
    static final int INF = 50000000;
    static final int NINF = -50000000;

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter pw = new PrintWriter(System.out);
        int N = sc.ni();
        int K = sc.ni();
        ArrayList<Integer>[] graph = new ArrayList[N];
        for (int i = 0; i < N; i++)
            graph[i] = new ArrayList<Integer>();
        for (int i = 0; i < N; i++) {
            int j = 0;
            while (true) {
                j = sc.ni()-1;
                if (j==-1)
                    break;
                graph[i].add(j);
            }
        }

        int[][][] dp0 = new int[N][N][2]; //maximum number of stages constrained between i and j (excluded) counterclockwise given that we are currently at i if k=0 and j if k=1.
        for (int size = 2; size <= N; size++) {
            for (int i = 0; i < N; i++) {
                int j = (i+size)%N;
                for (int k: graph[i]) {
                    if (inRangeEx(i,j,k)) {
                        dp0[i][j][0] = Math.max(dp0[i][j][0],1+Math.max(dp0[i][k][1],dp0[k][j][0]));
                    }
                }
                for (int k: graph[j]) {
                    if (inRangeEx(i,j,k)) {
                        dp0[i][j][1] = Math.max(dp0[i][j][1],1+Math.max(dp0[i][k][1],dp0[k][j][0]));
                    }
                }
            }
        }
        
        //Calculate another DP which is the maximum number of non-intersecting stages that begin in i (0 to N-1)
        //and end in j (0 to N-1) and are constrained by the interval [i,j] (inclusive). If 0 then we go CCW, if 1 we go CW.
        int[][][] dpDirect = new int[N][N][2];
        for (int i = 0; i < N; i++) {
        	for (int j = 0; j < N; j++) {
        		Arrays.fill(dpDirect[i][j], NINF);
        	}
        }
        for (int j = 0; j < N; j++) {
        	Arrays.fill(dpDirect[j][j], 0);
            for (int idx = 1; idx < N; idx++) {
                int iCCW = (j-idx+N)%N;
                for (int k: graph[iCCW]) {
                    if (inRangeIn(iCCW,j,k)) {
                        dpDirect[iCCW][j][0] = Math.max(dpDirect[iCCW][j][0],1+dpDirect[k][j][0]);
                    }
                }
                int iCW = (j+idx)%N;
                for (int k: graph[iCW]) {
                    if (inRangeIn(j,iCW,k)) {
                        dpDirect[iCW][j][1] = Math.max(dpDirect[iCW][j][1],1+dpDirect[k][j][1]);
                    }
                }
            }
        }

        int ans0 = 0;
        int h0 = 0;
        for (int i = 0; i < N; i++) {
            int val = dp0[i][i][0];
            if (val > ans0) {
                ans0 = val;
                h0 = i+1;
            }
        }

        int ans1 = 0;
        int h1 = 0;
        //given an intersection: final route is a->b->...->c->d->... with edges (a,b) and (c,d) intersecting
        for (int a = 0; a < N; a++) {
            for (int b: graph[a]) {
                for (int c = 0; c < N; c++) {
                    if (c==a||c==b)
                        continue;
                    for (int d: graph[c]) {
                        if (d==a||d==b)
                            continue;

                        if (cross(a,b,c,d)) {

                        	int val = 2;
                        	if (inRangeEx(a,b,c)) {
                        		val += dpDirect[b][c][1];
                        		val += Math.max(dp0[d][a][0],dp0[b][d][1]);
                        	} else {
                        		val += dpDirect[b][c][0];
                        		val += Math.max(dp0[a][d][1],dp0[d][b][0]);
                        	}
                        	if (val > ans1) {
                        		ans1 = val;
                        		h1 = a+1;
                        	}
                        }
                    }
                }
            }
        }

        if (K==0||(ans0 > ans1)) {
            pw.println(ans0);
            pw.println(h0);
        } else {
            pw.println(ans1);
            pw.println(h1);
        }


        pw.close();
    }

    public static boolean cross(int a, int b, int c, int d) {
        int n1 = (inRangeEx(a,b,c)?1:0)+(inRangeEx(a,b,d)?1:0);
        int n2 = (inRangeEx(b,a,c)?1:0)+(inRangeEx(b,a,d)?1:0);
        return (n1==1&&n2==1);
    }

    //is k in between (i,j) given the wraparound
    public static boolean inRangeEx(int i, int j, int k) {
        if (i < j)
            return (i < k && k < j);
        else
            return (i < k || k < j);
    }

    //is k in between [i,j] given the wraparound
    public static boolean inRangeIn(int i, int j, int k) {
        if (i <= j)
            return (i <= k && k <= j);
        else
            return (i <= k || k <= j);
    }

    static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int ni() {
            return Integer.parseInt(next());
        }

        long nl() {
            return Long.parseLong(next());
        }

        double nd() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}

Compilation message

race.java:4: error: class Main is public, should be declared in a file named Main.java
public class Main {
       ^
Note: race.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error