Ladders

#include <bits/stdc++.h>

using namespace std;

bool topological_sort_rec(int n, vector<vector<int>> &adj, int *state, vector<int> &out, int x) {

    state[x] = 1;

    for (int p : adj[x]) {
        if (state[p] == 1)
            return false;
        else if (state[p] == 0) {
            bool r = topological_sort_rec(n, adj, state, out, p);
            if (!r) return false;
        }
    }

    state[x] = 2;
    out.push_back(x);   
        
    return true;

}

bool topological_sort(int n, vector<vector<int>> &adj, vector<int> &out) {

    int *state = new int[n];
    for (int i = 0; i < n; i++)
        state[i] = 0;
    
    for (int i = 0; i < n; i++) {
        if (state[i] == 0) {
            // not yet visited
            bool r = topological_sort_rec(n, adj, state, out, i);
            if (!r) return false;
        }
    }

    reverse(out.begin(), out.end());
    return true;

}

int main() {

    int n;
    cin >> n;

    vector<int> A(n);
    for (int i = 0; i < n; i++)
        cin >> A[i];
    
    if (n == 1) {
        cout << 0 << endl;
        return 0;
    } else if (n == 2) {
        cout << 1 << endl;
        return 0;
    }
    
    map<int, int> index_of_num;

    for (int i = 0; i < n; i++)
        index_of_num[A[i]] = i;

    vector<vector<int>> adj(n);

    for (int pos = n-1; pos >= 1; pos--) {

        int value = A[pos];

        for (int div = 1; div <= value/2; div++) {
            if (value % div == 0) {
                int index_of_div = index_of_num[div];
                if (index_of_div < pos-1)
                    adj[index_of_div].push_back(pos);
            }
        }

        adj[pos-1].push_back(pos);

    }

    vector<int> order;
    topological_sort(n, adj, order);
    
    vector<int> num_moves_required(n);
    num_moves_required[n-1] = 0;
    num_moves_required[n-2] = 1;

    for (int pos = n-3; pos >= 0; pos--) {

        int minimum = INT_MAX;

        for (int x : adj[pos]) {
            minimum = min(minimum, num_moves_required[x]+1);
        }

        num_moves_required[pos] = minimum;
        
    }

    cout << num_moves_required[0] << endl;
    return 0;

}

/*
10
8 10 3 6 5 1 4 7 2 9
*/

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: WRONG ANSWER

Test 53

Verdict: WRONG ANSWER

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: WRONG ANSWER

Test 62

Verdict: TIME LIMIT EXCEEDED

Test 63

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Test 64

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Test 65

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Test 66

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Test 67

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Test 68

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Test 69

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Test 70

Verdict: TIME LIMIT EXCEEDED

Test 71

Verdict: TIME LIMIT EXCEEDED