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| class Solution {
public int fourSumCount(int[] nums1, int[] nums2, int[] nums3, int[] nums4) {
int res = 0;
Map<Integer, Integer> map1 = merge(nums1, nums2);
Map<Integer, Integer> map2 = merge(nums3, nums4);
for(Map.Entry<Integer, Integer> entry : map1.entrySet()){
Integer key = entry.getKey();
Integer value1 = entry.getValue();
if(map2.containsKey((0 - key))){
Integer value2 = map2.get((0 - key));
res += value1 * value2;
}
}
return res;
}
public Map<Integer, Integer> merge(int[] nums1, int[] nums2){
Map<Integer, Integer> map = new HashMap<>();
for(int i = 0; i < nums1.length; i++){
for(int j = 0; j < nums2.length; j++){
Integer value = nums1[i] + nums2[j];
map.put(value, map.getOrDefault(value, 0) + 1);
}
}
return map;
}
}
|
