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  1. #include <iostream>
  2. #include<bits/stdc++.h>
  3. using namespace std;
  4.  
  5.  
  6. // leetcode 323
  7.  
  8. int threeSumMulti(vector<int>& nums, int target) {
  9.         int cnt = 0;
  10.         int mod=1e9+7;
  11.           unordered_map<int, int> mpp;
  12.  
  13.  
  14.         for (int k = 2; k < nums.size(); k++) {
  15.             int x = target - nums[k];
  16.  
  17.  
  18.             for (int j = 0; j < k; j++) {
  19.                 int find = x - nums[j];
  20.                 if (mpp.count(find)) {
  21.                     cnt = (cnt + mpp[find])%mod;
  22.  
  23.  
  24.                 }
  25.                 mpp[nums[j]]++;
  26.  
  27.             }
  28.             mpp.clear();
  29.  
  30.         }
  31.         return cnt;
  32.     }
  33.  
  34.  
  35.  
  36. int main() {
  37. 	int n,target;
  38. 	cin>>n>>target;
  39. 	vector<int> nums(n);
  40. 	for(int i=0;i<n;i++){
  41. 		cin>>nums[i];
  42. 	}
  43.  
  44. 	int a = threeSumMulti(nums,target);
  45. 	cout<<a;
  46.  
  47.  
  48. 	return 0;
  49. }
Success #stdin #stdout 0s 5324KB
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https://ideone.com/SfsmhJ
language:
C++14 (gcc 8.3)
created:
6 hours ago
visibility:
public

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