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Discover the Nation with none outgoing path from given Graph

Given a 2D array arr[][], the place arr[i] = [Ai, Bi] means there exists a direct path going from nation Ai to nation Bi, the duty is to discover a nation with out an outgoing path.

Be aware: It’s assured that there can be just one such nation and the given graph doesn’t comprise any cycle.

Examples:

Enter: arr = {{“Germany”, ” Japan”}, {“United States”, “India”}, {“Japan”, “United States”}}
Output: “India”
Rationalization: Ranging from “Germany” you’ll attain the vacation spot nation “India”. Journey consists of: “Germany” -> “Japan”  -> “United States”  -> “India”.

Enter: arr= [[“B”, “C”], [“D”, “B”], [“C”, “A”]]
Output: “A”

An method utilizing Hashing:

The thought is to map each route A -> B. This can maintain a bit of knowledge that from A we will attain to B. Now Iterate over all nation B, and examine if there exists any route from B to every other nation. If not then that is th required reply.

Comply with the steps under to implement the above thought:

• Initialize a map for mapping all nation routes.
• Iterate over the given array arr[][].
• Map all nation routes A->B into the map.
• Initialize a variable end result, which can retailer the specified nation.
• Iterate over the given array arr[][]
• Verify if there exists any outgoing route to a different nation.
• If not, then save this as the specified nation.
• Return the end result.

Beneath is the implementation of the above method.

C++

 ` `  `#embody ` `utilizing` `namespace` `std;` ` `  `string destCountry(vector >& arr)` `{` `    ` `    ` `    ``unordered_map unmap;` ` `  `    ` `    ``for` `(``auto` `s : arr)` `        ``unmap[s[0]] = s[1];` ` `  `    ` `    ` `    ``string end result = ``""``;` ` `  `    ` `    ``for` `(``auto` `s : arr) {` ` `  `        ` `        ` `        ` `        ` `        ``if` `(unmap.discover(s[1]) == unmap.finish()) {` `            ``end result = s[1];` `            ``break``;` `        ``}` `    ``}` ` `  `    ` `    ``return` `end result;` `}` ` `  `int` `predominant()` `{` `    ``vector > arr` `        ``= { { ``"Germany"``, ``"Japan"` `},` `            ``{ ``"United States"``, ``"India"` `},` `            ``{ ``"Japan"``, ``"United States"` `} };` ` `  `    ` `    ``cout << destCountry(arr);` ` `  `    ``return` `0;` `}`

Time Complexity: O(N)
Auxiliary House: O(N)