Submission #1300981

#TimeUsernameProblemLanguageResultExecution timeMemory
1300981baotoan655Railway Trip (JOI17_railway_trip)C++20
100 / 100
84 ms15044 KiB
#include <bits/stdc++.h>
#define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
using namespace std;

const int N = 1e5 + 5, LG = 17;
int n, k, q;
int a[N];
int dep[N];
int nl[N][LG], nr[N][LG];
int st[N];


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

//    file("A") else file("task");

    cin >> n >> k >> q;
    for(int i = 1; i <= n; ++i) cin >> a[i];
    a[0] = a[n + 1] = 1e9;
    for(int i = 1; i <= n; ++i) {
        while(st[0] && a[st[st[0]]] < a[i]) --st[0];
        if(st[0]) nl[i][0] = st[st[0]];
        else nl[i][0] = 1;
        st[++st[0]] = i;
    }
    for(int i = n; i >= 1; --i) {
        while(st[0] && a[st[st[0]]] < a[i]) --st[0];
        if(st[0]) nr[i][0] = st[st[0]];
        else nr[i][0] = n;
        st[++st[0]] = i;
    }
    for(int j = 1; j < LG; ++j) {
        for(int i = 1; i <= n; ++i) {
            nl[i][j] = min(nl[nl[i][j - 1]][j - 1], nl[nr[i][j - 1]][j - 1]);
            nr[i][j] = max(nr[nr[i][j - 1]][j - 1], nr[nl[i][j - 1]][j - 1]);
        }
    }
    for(int _ = 1; _ <= q; ++_) {
        int a, b;
        cin >> a >> b;
        if(a > b) swap(a, b);
        int l = a, r = a, ans = 0, c;
        for(int i = LG - 1; i >= 0; --i) {
            if(max(nr[l][i], nr[r][i]) < b) {
                tie(l, r) = make_pair(min(nl[l][i], nl[r][i]), max(nr[l][i], nr[r][i]));
                ans += (1 << i);
            }
        }
        c = r;
        l = b, r = b;
        for(int i = LG - 1; i >= 0; --i) {
            if(min(nl[l][i], nl[r][i]) > c) {
                tie(l, r) = make_pair(min(nl[l][i], nl[r][i]), max(nr[l][i], nr[r][i]));
                ans += (1 << i);
            }
        }
        cout << ans << '\n';
    }
    return 0;
}

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