Merge pull request #493 from shashank-556/fix

update Two_sum.cpp

Author: amritansh22

Two_Sum.cpp

@@ -1,27 +1,23 @@
-// Two_Sum
 /*
-	Given an array of integers nums(sorted in ascending order) and an integer target,
+	Given an array of integers and an integer target,
 	return indices(zero indexed) of the two numbers if exists such that they sum adds up to target.
 */
 #include<bits/stdc++.h>
 using namespace std;
 
 vector<int> Two_Sum(vector<int> &arr, int target) {
 
-	int low = 0, high = arr.size() - 1;
-	while (low <= high) {
-		int sum = arr[low] + arr[high];
-		if (target == sum) {
-			return {low, high};
-		}
-		else if (target < sum) {
-			high--;
-		}
-		else {
-			low++;
-		}
-	}
-	return { -1, -1};
+	std::unordered_map<int,int> mp;
+
+	for(int i=0;i<arr.size();i++){
+
+	if(mp.find(target-arr[i])!=mp.end())
+		return {mp[target-arr[i]],i};
+
+	mp[arr[i]]=i;
+}
+
+return {-1,-1};
 }
 
 int main()
@@ -43,8 +39,8 @@ int main()
 	vector<int> p = Two_Sum(arr, target);
 
 	if (p[0] == -1 && p[1] == -1)
-		cout << "Two numbers not exist in array" << endl;
+		cout << "Two numbers with sum "<<target<< " are not present in the array" << endl;
 	else
 		cout << "Indices are " << p[0] << " and " << p[1] << endl;
 	return 0;
-}
+}