Submission #260538

#	Time	Username	Problem	Language	Result	Execution time	Memory
260538		georgerapeanu	Sailing Race (CEOI12_race)	C++11	5 / 100	609 ms	5120 KiB

race

#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

int n;
int k;

const int NMAX = 500;

int dp[NMAX + 5][NMAX + 5][2];
int force[NMAX + 5][NMAX + 5][2];
int bst[NMAX + 5][NMAX + 5];

vector<int> graph[NMAX + 5];
vector<int> graphT[NMAX + 5];

bool is_in(int st,int dr,int pos){
    if(st <= dr){
        return st < pos && pos < dr;
    }
    return st < pos || pos < dr;
}

int nxt(int pos,int d = 1){
    return (pos + d - 1) % n + 1;
}

int ant(int pos){
    return nxt(pos,n - 1);
}

int dist(int i,int j){
    if(j >= i){
        return j - i;
    }
    return i + n - j;
}

int main(){

    scanf("%d %d",&n,&k);

    for(int i = 1;i <= n;i++){
        int u = i,v = -1;
        while(scanf("%d",&v) == 1){
            if(v == 0){
                break;
            }
            graph[u].push_back(v);
            graphT[v].push_back(u);
        }
    }

    for(int i = 1;i <= n;i++){
        for(int j = 1;j <= n;j++){
            dp[i][j][0] = -2 * n * (i != j);
            dp[i][j][1] = -2 * n * (i != j);
            force[i][j][0] = -2 * n * (i != j);
            force[i][j][1] = -2 * n * (i != j);
        }
    }

    for(int l = 1;l < n;l++){
        for(int i = 1;i <= n;i++){
            int j = nxt(i,l);
            for(auto it:graph[i]){
                if(is_in(i,j,it)){
                    dp[i][j][0] = max(dp[i][j][0],1 + max(dp[it][j][0],dp[nxt(i)][it][1]));
                    force[i][j][0] = max(force[i][j][0],1 + force[it][j][0]);
                }
            }
            for(auto it:graph[j]){
                if(is_in(i,j,it)){
                    dp[i][j][1] = max(dp[i][j][1],1 + max(dp[i][it][1],dp[it][ant(j)][0]));
                    force[i][j][1] = max(force[i][j][1],1 + force[i][it][1]);
                }
            }
        }
    }

    int ans = 0;
    int fst = -1;

    for(int i = 1;i <= n;i++){
        for(auto it:graph[i]){
            int a = dp[nxt(i)][it][1];
            int b = dp[it][ant(i)][0];
            if(ans < 1 + max(a,b)){
                ans = 1 + max(a,b);
                fst = i;
            }
        }
    }

    if(k){

        for(int j = 1;j <= n;j++){
            for(int k = nxt(j);k != j;k = nxt(k)){
                int bst_ext = -1;
                int bst_int = -1;
                for(auto i:graphT[j]){
                    if(is_in(j,k,i) == false){
                        if(bst_ext == -1 || dist(k,i) < dist(k,bst_ext)){
                            bst_ext = i;
                        }
                    }
                    else{
                        if(bst_int == -1 || dist(i,k) < dist(bst_int,k)){
                            bst_int = i;
                        }
                    }
                }
                for(auto l:graph[k]){
                    if(is_in(j,k,l) == false){
                        if(bst_ext != -1 && is_in(k,l,bst_ext)){
                            int a = dp[l][ant(j)][0];
                            int b = dp[nxt(bst_ext)][l][1]; 
                            if(ans < 2 + max(a,b) + force[j][k][0]){
                                ans = 2 + max(a,b) + force[j][k][0];
                                //printf("%d %d %d %d and %d %d %d\n",j,k,l,bst_ext,force[j][k][0],a,b);
                                fst = bst_ext;
                            }
                        }
                    }
                    else{
                        if(bst_int != -1 && is_in(l,k,bst_int)){
                            int a = dp[nxt(j)][l][1];
                            int b = dp[l][ant(bst_int)][0]; 
                            if(ans < 2 + max(a,b) + force[k][j][1]){
                                ans = 2 + max(a,b) + force[k][j][1];
                                //printf("%d %d %d %d and %d %d %d\n",j,k,l,bst_int,force[k][j][1],a,b);
                                fst = bst_int;
                            }
                        }
                    }
                }
            }
        }
    }

    printf("%d\n%d\n",ans,fst);

    return 0;
}

Compilation message (stderr)

race.cpp: In function 'int main()':
race.cpp:43:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d",&n,&k);
     ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 5 / 100