LeetCode 1501: Countries You Can Safely Invest In

Explanation

To find the countries where you can safely invest in, we need to determine if there exists a path from one country to another such that the total number of distinct countries in that path is less than or equal to a given threshold threshold. This can be modeled as a graph problem where each country is a node in the graph, and there is an edge between two countries if they share a common border.

We can solve this problem using Depth-First Search (DFS) algorithm starting from each country. We will keep track of the number of distinct countries visited in the current path and stop exploring further if this count exceeds the given threshold.

class Solution {
    public List<Integer> mostVisited(int n, int[] rounds) {
        List<Integer> result = new ArrayList<>();
        int start = rounds[0];
        int end = rounds[rounds.length - 1];
        
        if (start <= end) {
            for (int i = start; i <= end; i++) {
                result.add(i);
            }
        } else {
            for (int i = 1; i <= end; i++) {
                result.add(i);
            }
            for (int i = start; i <= n; i++) {
                result.add(i);
            }
        }
        
        return result;
    }
}