Submission #969698

#	Time	Username	Problem	Language	Result	Execution time	Memory
969698		europium	Road Closures (APIO21_roads)	C++17	7 / 100	37 ms	9052 KiB

roads

#include "roads.h"

#include <vector>
#include <bits/stdc++.h>

using namespace std;
using ll = long long;

vector<ll> minimum_closure_costs(int n, vector<int> U, vector<int> V, vector<int> w) {
    vector<ll> ans(n, ll(0));

    // chain
    // k = 0 --> close all roads
    // k = 1 --> DP solution
    // k >= 2 --> don't need to close any road, 0

    ll cost = accumulate(w.begin(), w.end(), ll(0));
    ans[0] = cost;

    vector<vector<ll>> dp(n - 1, vector<ll>(2, (ll)0));

    // dp[i][j]
    // i - current index
    // j - 0 or 1. 1 means block the current road. 0 means don't block.

    dp[0][0] = 0;
    dp[0][1] = w[0];

    for (int i = 1; i < n - 1; i ++) {
        // current index is unblocked, which means that the previous road segment must be blocked
        // because we cannot have 2 consecutive unblocked segments
        dp[i][0] = dp[i-1][1];

        // current index is blocked. The previous road segment can be blocked or unblocked.
        dp[i][1] = w[i] + min(dp[i-1][1], dp[i-1][0]);
    }

    ans[1] = min(dp[n-2][0], dp[n-2][1]);

    return ans;
}

• Subtask 1: 0 / 5
• Subtask 2: 7 / 7
• Subtask 3: 0 / 14
• Subtask 4: 0 / 10
• Subtask 5: 0 / 17
• Subtask 6: 0 / 25
• Subtask 7: 0 / 22