Submission #259567

#	Time	Username	Problem	Language	Result	Execution time	Memory
259567		dantoh000	Secret Permutation (RMI19_permutation)	C++14	100 / 100	867 ms	376 KiB

permutation

#include <bits/stdc++.h>
#include "permutationc.h"
using namespace std;

int n;
int Query(vector<int> q){
    int a[n];
    for (int i = 0; i < n; i++){
        a[i] = q[i];
    }
    return query(a);
}

int d[257];
int vis[257];
int P[257];
bool findperm(int id){
    if (id == n) return abs(P[n-1]-P[0]) == d[id];
    int last = P[id-1];
    int dif = d[id];
    //printf("%d: %d +- %d\n",id,last,dif);
    int cur = last+dif;
    if (cur >= 1 && cur <= n && !vis[cur]){
        P[id] = cur;
        vis[cur] = 1;
        if (findperm(id+1)) return true;
        vis[cur] = 0;
        P[id] = 0;
    }
    cur = last-dif;
    if (cur >= 1 && cur <= n && !vis[cur]){
        P[id] = cur;
        vis[cur] = 1;
        if (findperm(id+1)) return true;
        vis[cur] = 0;
        P[id] = 0;
    }
    return false;
}

void solve(int _N){
    n = _N;
    vector<int> _p;
    vector<int> q;
    for (int i = 1; i <= n; i++){
        q.push_back(i);
    }
    srand(1232323);
    random_shuffle(q.begin(),q.end());
    for (auto x : q) _p.push_back(x);
    d[n] = Query(q);
    for (int j = n-1; j >= 1; j--){
        q.insert(q.begin(),q.back());
        q.pop_back();
        d[j] = Query(q);
    }
    int sum = 0;
    for (int i = 1; i <= n; i++){
        sum += d[i];
    }
    assert(sum % (n-1) == 0);
    sum /= n-1;
    for (int i = 1; i <= n; i++){
        d[i] = sum-d[i];
        //printf("%d ",d[i]);
        //assert(d[i] == abs(ans[i-1]-ans[i%N]));
    }
    //printf("\n");
    for (int i = 1; i <= n; i++){
        vis[i] = 1;
        P[0] = i;
        if (findperm(1)){
            int ret[n+1];
            for (int i = 0; i < n; i++){
                ret[_p[i]-1] = P[i];
            }
            answer(ret);
            return;
        }
        vis[i] = 0;
    }
}

Compilation message (stderr)

stub.cpp: In function 'int query(int*)':
stub.cpp:15:9: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   fscanf(stdin, "%d", &x);
   ~~~~~~^~~~~~~~~~~~~~~~~
stub.cpp: In function 'int main(int, char**)':
stub.cpp:48:9: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   fscanf(stdin, "%d", &N);
   ~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 50 / 50