LeetCode 465: Optimal Account Balance

DFS to search all possible combine.

class Solution {
    public int minTransfers(int[][] transactions) {
        if (transactions.length == 0) return 0;
        int nums = 0;
        for (int[] trans : transactions) {
            nums = Math.max(nums, Math.max(trans[0], trans[1]));
        }
        int[] debt = new int[nums + 1];
        for (int[] trans : transactions) {
            debt[trans[0]] += trans[2];
            debt[trans[1]] -= trans[2];
        }

        return dfs(debt, 0, 0);
    }
    
    private int dfs(int[] debt, int index, int count) {
        while (index < debt.length && debt[index] == 0) index++;
        int result = Integer.MAX_VALUE;
        for (int i = index + 1, prev = 0; i < debt.length; i++) {
            if (debt[i] != prev && debt[i] * debt[index] < 0) {
                debt[i] += debt[index];
                result = Math.min(result, dfs(debt, index + 1, count + 1));
                debt[i] -= debt[index];
                prev = debt[i];
            }
        }
        return result < Integer.MAX_VALUE ? result : count;
    }
}