Submission #1061777

#	Time	Username	Problem	Language	Result	Execution time	Memory
1061777		RecursiveCo	Sky Walking (IOI19_walk)	C++17	33 / 100	206 ms	25788 KiB

walk

#include <bits/stdc++.h>
#include "walk.h"

using namespace std;

long long min_distance(vector<int> x, vector<int> h, vector<int> l, vector<int> r, vector<int> y, int s, int g) {
    // Assume s = 0, g = n - 1 and h consists of equal elements.
    int n = x.size(); // = h.size()
    int m = l.size(); // = r.size() = y.size()
    long long ans = x[n - 1] - x[0];
    map<pair<int, int>, long long> dp;
    vector<array<int, 4>> events;
    for (int i = 0; i < m; i++) {
        events.push_back({r[i] - 1, y[i], i, 1});
        events.push_back({l[i] - 1, y[i], i, 0});
    }
    sort(events.rbegin(), events.rend());
    vector<vector<int>> right(n);
    for (int i = 0; i < m; i++) right[r[i]].push_back(i);
    set<pair<int, int>> open;
    int ptr = 0;
    for (int i = n - 1; i >= 0; i--) {
        while (ptr < 2 * m && events[ptr][0] >= i) {
            int yc = events[ptr][1];
            int ind = events[ptr][2];
            int typ = events[ptr][3];
            if (typ) {
                open.insert({yc, ind});
            } else {
                open.erase({yc, ind});
            }
            ptr++;
        }
        for (int ind: right[i]) {
            long long val = 1e18;
            auto it = open.lower_bound({y[ind], -1});
            if (it != open.end()) {
                val = min(val, (long long) ((*it).first - y[ind]) + dp[{r[(*it).second], (*it).first}]);
            }
            if (it != open.begin()) {
                it--;
                val = min(val, (long long) (y[ind] - (*it).first) + dp[{r[(*it).second], (*it).first}]);
            }
            dp[{i, y[ind]}] = i == n - 1? y[ind]: val;
        }
    }
    long long extra = 1e18;
    for (int i = 0; i < m; i++) {
        if (l[i] == 0) {
            extra = min(extra, y[i] + dp[{r[i], y[i]}]);
        }
    }
    ans += extra;
    if (ans >= 1e18) return -1;
    return ans;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 14
• Subtask 3: 15 / 15
• Subtask 4: 18 / 18
• Subtask 5: 0 / 43