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g0401_0500.s0454_4sum_ii.Solution Maven / Gradle / Ivy

package g0401_0500.s0454_4sum_ii;

// #Medium #Top_Interview_Questions #Array #Hash_Table
// #2022_07_18_Time_133_ms_(95.19%)_Space_42.4_MB_(88.53%)

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

public class Solution {
    public int fourSumCount(int[] nums1, int[] nums2, int[] nums3, int[] nums4) {
        int count = 0;
        Map map = new HashMap<>();
        for (int k : nums3) {
            for (int i : nums4) {
                int sum = k + i;
                map.put(sum, map.getOrDefault(sum, 0) + 1);
            }
        }
        for (int k : nums1) {
            for (int i : nums2) {
                int m = -(k + i);
                count += map.getOrDefault(m, 0);
            }
        }
        return count;
    }
}