Submission #135036

#	Time	Username	Problem	Language	Result	Execution time	Memory
135036		osaaateiasavtnl	Xylophone (JOI18_xylophone)	C++14	100 / 100	284 ms	644 KiB

xylophone

#include<bits/stdc++.h>
using namespace std;
#ifdef HOME
#else
#include "xylophone.h"
#endif

const int N = 5001;

#ifdef HOME
const int INF = 1e9 + 7;
int n;
int a[N];
int query(int l, int r) {
    int mn = INF, mx = -INF;
    for (int i = l; i <= r; ++i) {
        mn = min(mn, a[i]);
        mx = max(mx, a[i]);
    }   
    return mx - mn;
}   
void answer(int i, int x) {

}   
#endif

int ans[N];
int mem[2][N];
bool t[N], r[N];
int cnt[N];
bool check(int n) {
    for (int i = 1; i <= n; ++i) {
        if (ans[i] < 1 || ans[i] > n) return 0;
    }   
    for (int i = 1; i <= n; ++i) {
        cnt[i] = 0;
    }   
    for (int i = 1; i <= n; ++i) {
        ++cnt[ans[i]];
    }   
    for (int i = 1; i <= n; ++i) {
        if (cnt[i] != 1) {
            return 0;
        }
    }   
    int p1, pn;
    for (int i = 1; i <= n; ++i) {
        if (ans[i] == 1) p1 = i;
        if (ans[i] == n) pn = i;
    }   
    if (pn < p1) return 0;
    return 1;
}   
void solve(int n) {
    for (int i = 1; i + 1 <= n; ++i) {
        mem[0][i] = query(i, i + 1);
    }           
    for (int i = 1; i + 2 <= n; ++i) {
        mem[1][i] = query(i, i + 2);
    }   
    for (int i = 1; i + 2 <= n; ++i) {
        t[i + 2] = (mem[0][i] + mem[0][i + 1]) != mem[1][i];
    }   
    for (int i = 1; i <= n; ++i) {
        r[i] = r[i - 1] ^ t[i];
    }
    #ifdef HOME
    for (int i = 1; i <= n; ++i) {
        cout << r[i] << ' ';
    }   
    cout << '\n';
    #endif
    for (int f = 1; f <= n; ++f) {
        ans[1] = f;
        for (int i = 2; i <= n; ++i) {
            if (r[i]) {
                ans[i] = ans[i - 1] + mem[0][i - 1];
            }   
            else {
                ans[i] = ans[i - 1] - mem[0][i - 1];
            }   
        }   
        if (check(n)) {
            for (int i = 1; i <= n; ++i) {
                answer(i, ans[i]);
            }   
            return;
        }   
        ans[1] = f;
        for (int i = 2; i <= n; ++i) {
            if (r[i]) {
                ans[i] = ans[i - 1] - mem[0][i - 1];
            }   
            else {
                ans[i] = ans[i - 1] + mem[0][i - 1];
            }   
        }   
        if (check(n)) {
            for (int i = 1; i <= n; ++i) {
                answer(i, ans[i]);
            }   
            return;
        }   
    }
}   
#ifdef HOME
signed main() {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
    }   
    solve(n);
    for (int i = 1; i <= n; ++i) {
        cout << ans[i] << ' ';
    }   
    cout << '\n';
}   
#endif

Compilation message (stderr)

xylophone.cpp: In function 'bool check(int)':
xylophone.cpp:51:5: warning: 'pn' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (pn < p1) return 0;
     ^~
xylophone.cpp:51:5: warning: 'p1' may be used uninitialized in this function [-Wmaybe-uninitialized]

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