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802.java
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802.java
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__________________________________________________________________________________________________
sample 5 ms submission
class Solution {
public List<Integer> eventualSafeNodes(int[][] graph) {
List<Integer> res = new ArrayList<>();
if (graph == null || graph.length == 0)
return res;
int[] visited = new int[graph.length];
for (int i = 0; i < graph.length; i++) {
if (helper(graph, visited, i))
res.add(i);
}
return res;
}
public boolean helper(int[][] graph, int[] visited, int i) {
if (visited[i] != 0)
return visited[i] == 1;
visited[i] = 2;
for (int num : graph[i])
if (!helper(graph, visited, num))
return false;
visited[i] = 1;
return true;
}
}
__________________________________________________________________________________________________
sample 63468 kb submission
class Solution {
public List<Integer> eventualSafeNodes(int[][] graph) {
List<Integer> ans = new ArrayList<>();
boolean[] visited = new boolean[graph.length];
boolean[] cycles = new boolean[graph.length];
for(int i=0; i<graph.length; i++){
if(!visited[i])
dfs(i, graph, visited, new boolean[graph.length], cycles);
}
for(int i=0; i<graph.length; i++){
if(!cycles[i])
ans.add(i);
}
return ans;
}
void dfs(int node, int[][] graph, boolean[] visited, boolean[] visiting, boolean[] cycles){
if(cycles[node] || visiting[node]){
cycles[node] = true;
return;
} else if(visited[node])
return;
visiting[node] = true;
for(int child: graph[node]){
dfs(child, graph, visited, visiting, cycles);
if(cycles[child])
cycles[node] = true;
}
visiting[node] = false;
visited[node] = true;
}
}
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