Submission #276420

#	Time	Username	Problem	Language	Result	Execution time	Memory
276420		toonewbie	Xylophone (JOI18_xylophone)	C++17	100 / 100	93 ms	632 KiB

xylophone

#include "xylophone.h"
#include <bits/stdc++.h>
using namespace std;
int A[5001];
int pos[5001];
void solve(int N) {
    int id;
    int l = 1, r = N;
    while(r - l >= 0) {
        int mid = (l + r) >> 1;
        if (query(mid, N) != N - 1) {
            id = mid - 1;
            r = mid - 1;
        } else {
            l = mid + 1;
        }
    }
    A[id] = 1;
    pos[1] = id;
    if (id > 1) {
        A[id - 1] = 1 + query(id - 1, id);
        pos[A[id - 1]] = id - 1;
    }
    A[id + 1] = 1 + query(id, id + 1);
    pos[A[id + 1]] = id + 1;
    for (int j = id - 2; j >= 1; j--) {
        int dif = query(j, j + 1), sgn;
        if (A[j + 1] + dif > N || pos[A[j + 1] + dif]) sgn = -1;
        else if (A[j + 1] - dif <= 0 || pos[A[j + 1] - dif]) sgn = 1;
        else if (max({A[j + 1] + dif, A[j + 1], A[j + 2]}) - min({A[j + 1] + dif, A[j + 1], A[j + 2]}) == query(j, j + 2)) sgn = 1;
        else sgn = -1;
        A[j] = A[j + 1] + sgn * dif;
        pos[A[j]] = j;
    }
    for (int j = id + 2; j <= N; j++) {
        int dif = query(j - 1, j), sgn;
        if (A[j - 1] + dif > N || pos[A[j - 1] + dif]) sgn = -1;
        else if (A[j - 1] - dif <= 0 || pos[A[j - 1] - dif]) sgn = 1;
        else if (max({A[j - 1] + dif, A[j - 1], A[j - 2]}) - min({A[j - 1] + dif, A[j - 1], A[j - 2]}) == query(j - 2, j)) sgn = 1;
        else sgn = -1;
        A[j] = A[j - 1] + sgn * dif;
        pos[A[j]] = j;
    }
    for (int i = 1; i <= N; i++) {
        answer(pos[i], i);
    }
}

Compilation message (stderr)

xylophone.cpp: In function 'void solve(int)':
xylophone.cpp:21:30: warning: 'id' may be used uninitialized in this function [-Wmaybe-uninitialized]
   21 |         A[id - 1] = 1 + query(id - 1, id);
      |                         ~~~~~^~~~~~~~~~~~

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