leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
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commit 152e80a8f793e797fe3edda9f4f7881d868c455b
parent f96db6a17ac23cf68683f19555c814040a19349f
author Dimitrije Dobrota < mail@dimitrijedobrota.com >
date Wed, 12 Jul 2023 20:20:12 +0200

Improved Daily Problem

Diffstat:
M Problems/0802.cpp | +++++++++++++++++++++++++++++++++++++++++ -------

1 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/ Problems/0802.cpp b/ Problems/0802.cpp

@@ -1,18 +1,16 @@

class Solution {
public:
vector<int> eventualSafeNodes(vector<vector<int>> &graph) {
vector<int> eventualSafeNodes(const vector<vector<int>> &graph) {
int n = graph.size();
vector<int> res;
vector<bool> visited(n, false);
vector<bool> safe(n, false);
vector<bool> visited(n, false), safe(n, false);
stack<int> st;
for (int i = 0; i < n; i++) {
if (visited[i]) continue;
st.push(i);
while (!st.empty()) {
int root = st.top();
st.pop();
if (root == -1) {
st.pop();
root = st.top();
st.pop();
bool s = true;

@@ -24,16 +22,52 @@ public:

safe[root] = s;
continue;
}
if (visited[root]) continue;
if (visited[root]) {
st.pop();
continue;
};
visited[root] = true;
st.push(root);
st.push(-1);
for (int c : graph[root])
if (!visited[c]) st.push(c);
}
}
vector<int> res;
for (int i = 0; i < n; i++)
if (safe[i]) res.push_back(i);
return res;
}
};

// Cleaner code, more memory
class Solution {
int safe[100001] = {0}, count[10001] = {0};

public:
vector<int> eventualSafeNodes(const vector<vector<int>> &graph) {
int n = graph.size();
vector<vector<int>> adj(n);
for (int i = 0; i < n; i++) {
count[i] += graph[i].size();
for (int node : graph[i]) adj[node].push_back(i);
}

queue<int> q;
for (int i = 0; i < n; i++)
if (!count[i]) q.push(i);

while (!q.empty()) {
int root = q.front();
q.pop();
safe[root] = true;

for (auto node : adj[root])
if (!--count[node]) q.push(node);
}

vector<int> res;
for (int i = 0; i < graph.size(); i++)
if (safe[i]) res.push_back(i);
return res;
}
};