Максимален път в матрицa

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <climits>
#include <queue>

using namespace std;

unordered_map<int, vector<int>> graph;


int findMaxPath(int current, vector<int>& matrix, vector<int>& distances,  int finish) {
    if (distances[current] != -6000)
        return distances[current];
    if (current == finish)
        return matrix[finish];
    int result = INT_MIN;
    int curr;
    for (auto neighbour : graph[current])
    {
        curr = findMaxPath(neighbour, matrix, distances, finish);
        if (curr > result)
        {
            result = curr;
        }
    }
    return distances[current] = result + matrix[current];
}

int main() {
    int n, k, a, b;
    cin >> n;
    vector<int> matrix(n * n);
    vector<int> distances(n * n, -6000);

    for (int i = 0; i < n * n; i++) {
        cin >> matrix[i];
        if ((i + 1) % n != 0)
            graph[i].push_back(i + 1);
        if ((i + n) < n * n)
            graph[i].push_back(i + n);
    }
    cin >> k;
    for (int i = 0; i < k; i++) {
        cin >> a >> b;
        graph[(a - 1) * n + b - 1].push_back(a * n + b);
    }

    cout << findMaxPath(0, matrix, distances, n * n - 1);
}