https://leetcode.com/problems/flower-planting-with-no-adjacent/

flower-planting-with-no-adjacent.java

class Solution {
    public int[] gardenNoAdj(int N, int[][] paths) {
        Map<Integer, Set<Integer>> graph = new HashMap<>();
        for (int i = 1; i <= N; i++) {
            graph.put(i, new HashSet<>());
        }
        for (int[] path : paths) {
            graph.get(path[0]).add(path[1]);
            graph.get(path[1]).add(path[0]);
        }
        
        int[] result = new int[N];
        for (int i = 1; i <= N; i++) {
            int[] color = new int[5];
            for (int neighbor : graph.get(i)) {
                color[result[neighbor - 1]] += 1;
            }
            for (int j = 4; j > 0; --j) {
                if (color[j] == 0) {
                    result[i - 1] = j;
                }   
            }
        }
        
        return result;
    }
}