# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
291187 | Agnimandur | Sailing Race (CEOI12_race) | Java | 2639 ms | 65556 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
import java.io.*;
import java.util.*;
class race {
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];
ArrayList<Integer>[] transpose = new ArrayList[N];
for (int i = 0; i < N; i++) {
graph[i] = new ArrayList<Integer>();
transpose[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);
transpose[j].add(i);
}
}
for (int i = 0; i < N; i++) {
Collections.sort(graph[i]);
Collections.sort(transpose[i]);
}
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 = -1;
int h0 = -1;
for (int i = 0; i < N; i++) {
int val = dp0[i][i][0];
if (val > ans0) {
ans0 = val;
h0 = i+1;
}
}
int[][][] choice = new int[N][N][2];//point in the transpose of i that it closest to j (0 on the left, 1 on the right)
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
Arrays.fill(choice[i][j],-1);
if (i==j)
continue;
if (transpose[i].isEmpty())
continue;
int s = transpose[i].size();
if (transpose[i].get(0) > j) {
choice[i][j][0] = transpose[i].get(s-1);
choice[i][j][1] = transpose[i].get(0);
} else {
int low = 0;
int high = s-1;
while (low < high) {
int med = (low+high+1)/2;
if (transpose[i].get(med) > j) {
high = med-1;
} else {
low = med;
}
}
int L = transpose[i].get(low);
int R = transpose[i].get((low+1)%s);
if (L==j) {
Arrays.fill(choice[i][j],L);
} else {
choice[i][j][0] = L;
choice[i][j][1] = R;
}
}
}
}
//System.out.println(Arrays.deepToString(choice));
int ans1 = -1;
int h1 = -1;
//given an intersection: final route is a->b->...->c->d->... with edges (a,b) and (c,d) intersecting
for (int b = 0; b < N; b++) {
for (int c = 0; c < N; c++) {
if (c==b) continue;
for (int d: graph[c]) {
if (d==b)continue;
int a;
if (inRangeEx(c,d,b)) {
a = choice[b][c][0];
} else {
a = choice[b][c][1];
}
if (a==c||a==d||a==-1)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 (stderr)
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