_923.java

package com.fishercoder.solutions;

import java.util.HashMap;
import java.util.Map;

public class _923 {
    public static class Solution1 {
        public int threeSumMulti(int[] A, int target) {
            int MOD = 1000000007;
            Map<Integer, Long> map = new HashMap<>();
            for (int num : A) {
                map.put(num, map.getOrDefault(num, 0L) + 1);
            }
            long result = 0;
            for (int num1 : map.keySet()) {
                for (int num2 : map.keySet()) {
                    int num3 = target - num1 - num2;
                    if (map.containsKey(num3)) {
                        Long count1 = map.get(num1);
                        Long count2 = map.get(num2);
                        Long count3 = map.get(num3);
                        if (num1 == num2 && num1 == num3) {
                            result = (result + (count1 * (count1 - 1) * (count1 - 2) / 6)) % MOD;
                        } else if (num1 == num2 && num1 != num3) {
                            result = (result + (count1 * (count1 - 1) / 2) * count3) % MOD;
                        } else if (num1 < num2 && num2 < num3) {
                            result = (result + count1 * count2 * count3) % MOD;
                        }
                    }
                }
            }
            return (int) result;
        }
    }
}