leetcode

Daily Problem

2 files changed, 55 insertions(+), 0 deletions(-)

diff --git a/ Problems/2421.cpp b/ Problems/2421.cpp

@@ -0,0 +1,54 @@

class UnionFind {

int n, cnt = n;

vector<int> root, size;

public:

UnionFind(int n) : n(n), root(n), size(n, 1) {

iota(root.begin(), root.end(), 0);

}

int find(int x) {

while (x != root[x]) x = root[x] = root[root[x]];

return x;

}

void join(int x, int y) {

x = find(x), y = find(y);

if (x != y) {

if (size[x] > size[y]) swap(x, y);

root[x] = y;

size[y] += size[x];

cnt--;

}

}

};

class Solution {

public:

int numberOfGoodPaths(vector<int> &vals, vector<vector<int>> &edges) {

int n = vals.size();

map<int, vector<int>> valuesToNodes;

vector<vector<int>> adj(n);

UnionFind uf(n);

for (auto &edge : edges) {

adj[edge[0]].push_back(edge[1]);

adj[edge[1]].push_back(edge[0]);

}

for (int i = 0; i < n; i++) valuesToNodes[vals[i]].push_back(i);

int goodPaths = 0;

for (auto &[value, nodes] : valuesToNodes) {

for (int node : nodes) {

for (int neighbor : adj[node]) {

if (vals[node] >= vals[neighbor]) { uf.join(node, neighbor); }

}

}

unordered_map<int, int> group;

for (int u : nodes) group[uf.find(u)]++;

for (auto &[_, size] : group) goodPaths += (size * (size + 1) / 2);

}

return goodPaths;

}

};

diff --git a/ README.md b/ README.md

@@ -309,6 +309,7 @@ for solving problems. | 2368 | Medium | [Reachable Nodes With Restrictions](Problems/2368.cpp) | | 2374 | Medium | [Node With Highest Edge Score](Problems/2374.cpp) | | 2390 | Medium | [Removing Stars From a String](Problems/2390.cpp) |

| 2421 | Medium | [Number of Good Paths](Problems/2421.cpp) |

| 2461 | Medium | [Maximum Sum of Distinct Subarrays With Length K](Problems/2461.cpp) | | 2465 | Easy | [Number of Distinct Averages](Problems/2465.cpp) | | 2466 | Medium | [Count Ways To Build Good Strings](Problems/2466.cpp) |