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// 1557. Minimum Number of Vertices to Reach All Nodes
#include "leetcode.h"
/*
* given a directed acyclic graph, with 'n' vertices numbered from 0 to 'n - 1',
* and an array 'edges', where 'edges[i] = [fromi, toi]' representes a directed
* edge from node 'fromi' to node 'toi'. find the smallest set of vertices from
* which all nodes in the graph are reachale. it's guaranteed that a unique
* solution exists. notice you cano return the vertices in any order.
*/
class Solution {
public:
vector<int> findSmallestSetOfVertices(int n, vvd(int) & edges) {
vector<int> ans, seen(n);
for (auto e : edges)
seen[e[1]] = 1;
for (int i = 0; i < n; ++i)
if (!seen[i])
ans.push_back(i);
return ans;
}
};
int main() {
Solution obj;
vvd(int) e1 = {{0, 1}, {0, 2}, {2, 5}, {3, 4}, {4, 2}};
vvd(int) e2 = {{0, 1}, {2, 1}, {3, 1}, {1, 4}, {2, 4}};
for (auto i : obj.findSmallestSetOfVertices(6, e1))
printf("%d ", i); // expect: 0 3
printf("\n");
for (auto i : obj.findSmallestSetOfVertices(5, e2))
printf("%d ", i); // expect: 0 2 3
}
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