Submission #729339

#	Time	Username	Problem	Language	Result	Execution time	Memory
729339		stevancv	Passport (JOI23_passport)	C++14	46 / 100	101 ms	65264 KiB

passport

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 2500 + 2;
const int M = 2e5 + 2;
const int inf = 1e9;
int l[M], r[M], dp[N][N];
vector<int> g[N], ig[N];
void Uradi(int x) {
    queue<int> q;
    q.push(x);
    dp[x][x] = 0;
    while (!q.empty()) {
        int s = q.front(); q.pop();
        for (int u : g[s]) {
            if (dp[x][u] > dp[x][s] + 1) {
                q.push(u);
                dp[x][u] = dp[x][s] + 1;
            }
        }
    }
}
void Kontra(int x) {
    queue<int> q;
    q.push(x);
    dp[x][x] = 0;
    while (!q.empty()) {
        int s = q.front(); q.pop();
        for (int u : ig[s]) {
            if (dp[u][x] > dp[s][x] + 1) {
                q.push(u);
                dp[u][x] = dp[s][x] + 1;
            }
        }
    }
}
int st[4 * M], dpp[M];
void Add(int node, int l, int r, int x, int y) {
    smin(st[node], y);
    if (l == r) return;
    int mid = l + r >> 1;
    if (x <= mid) Add(2 * node, l, mid, x, y);
    else Add(2 * node + 1, mid + 1, r, x, y);
}
int Get(int node, int l, int r, int ql, int qr) {
    if (r < ql || qr < l) return inf;
    if (ql <= l && r <= qr) return st[node];
    int mid = l + r >> 1;
    return min(Get(2 * node, l, mid, ql, qr), Get(2 * node + 1, mid + 1, r, ql, qr));
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> l[i] >> r[i];
    }
    int qqq, x;
    cin >> qqq >> x;
    if (x == 1) {
        for (int i = 1; i < 4 * M; i++) st[i] = inf;
        for (int i = n; i >= 1; i--) {
            if (r[i] == n) dpp[i] = 1;
            else dpp[i] = Get(1, 1, n, i, r[i]) + 1;
            smin(dpp[i], inf);
            Add(1, 1, n, i, dpp[i]);
        }
        if (dpp[1] == inf) dpp[1] = -1;
        cout << dpp[1] << en;
        return 0;
    }
    for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) dp[i][j] = inf;
    for (int i = 1; i <= n; i++) {
        for (int j = l[i]; j < i; j++) {
            g[i].push_back(j);
            ig[j].push_back(i);
        }
        for (int j = i + 1; j <= r[i]; j++) {
            g[i].push_back(j);
            ig[j].push_back(i);
        }
    }
    Uradi(x);
    Kontra(1);
    Kontra(n);
    int ans = inf;
    if (x == 1 || x == n) {
        if (dp[x][n + 1 - x] == inf) dp[x][n + 1 - x] = -1;
        cout << dp[x][n + 1 - x] << en;
        return 0;
    }
    for (int i = 2; i < n; i++) smin(ans, dp[x][i] + dp[i][1] + dp[i][n] - 1);
    smin(ans, dp[x][1] + dp[1][n]);
    smin(ans, dp[x][n] + dp[n][1]);
    if (ans == inf) ans = -1;
    cout << ans << en;
    return 0;
}

Compilation message (stderr)

passport.cpp: In function 'void Add(int, int, int, int, int)':
passport.cpp:46:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   46 |     int mid = l + r >> 1;
      |               ~~^~~
passport.cpp: In function 'int Get(int, int, int, int, int)':
passport.cpp:53:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   53 |     int mid = l + r >> 1;
      |               ~~^~~

• Subtask 1: 6 / 6
• Subtask 2: 16 / 16
• Subtask 3: 24 / 24
• Subtask 4: 0 / 8
• Subtask 5: 0 / 46