Submission #505251

#	Time	Username	Problem	Language	Result	Execution time	Memory
505251		colossal_pepe	Xylophone (JOI18_xylophone)	C++17	100 / 100	74 ms	332 KiB

xylophone

#include <iostream>
#include <vector>
using namespace std;
 
int n;
vector<int> a, pos;
 
int query(int s, int t);
void answer(int i, int x);
 
int find1Pos() {
    int l = 1, r = n;
    while (r - l > 1) {
        int mid = (r + l) / 2;
        if (query(mid, n) == n - 1) l = mid;
        else r = mid - 1;
    }
    if (query(r, n) == n - 1) return r;
    return l;
}
 
int getVal(int cur, int p, int pp) {
    int d = query(min(cur, p), max(cur, p));
    if (a[p] + d > n or pos[a[p] + d] != -1) {
        return a[p] - d;
    } else if (a[p] - d < 1 or pos[a[p] - d] != -1) {
        return a[p] + d;
    } else {
        int e = query(min(cur, pp), max(cur, pp)), c = 1;
        if (a[p] > a[pp]) c = -1;
        return (e == abs(a[p] - a[pp]) + d ? a[p] - (c * d) : a[p] + (c * d));
    }
}
 
void solve(int N) {
    n = N;
    a.resize(n + 1), pos.resize(n + 1);
    for (int i = 1; i <= n; i++) {
        a[i] = pos[i] = -1;
    }
    pos[1] = find1Pos();
    a[pos[1]] = 1;
    for (int i = pos[1] - 1; i >= 1; i--) {
        a[i] = getVal(i, i + 1, i + 2);
        pos[a[i]] = i;
    }
    for (int i = pos[1] + 1; i <= n; i++) {
        a[i] = getVal(i, i - 1, i - 2);
        pos[a[i]] = i;
    }
    for (int i = 1; i <= n; i++) {
        answer(i, a[i]);
    }
}

• Subtask 1: 11 / 11
• Subtask 2: 36 / 36
• Subtask 3: 53 / 53