leetcode

Finish Medium Graph Problems

7 files changed, 181 insertions(+), 0 deletions(-)

diff --git a/ Problems/0787.cpp b/ Problems/0787.cpp

@@ -0,0 +1,31 @@

class Solution {

struct edge {

int d, w, s;

edge(int d, int w, int s = -1) : d(d), w(w), s(s) {}

friend bool operator<(const edge &e1, const edge &e2) {

return e1.w > e2.w;

}

};

public:

int findCheapestPrice(int n, vector<vector<int>> &flights, int src, int dst,

int k) {

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

for (auto &f : flights) adj[f[0]].push_back({f[1], f[2]});

vector<int> stop(n, INT_MAX);

priority_queue<edge> pq;

pq.push({src, 0, 0});

while (!pq.empty()) {

auto [d, w, s] = pq.top();

pq.pop();

if (s > stop[d] || s > k + 1) continue;

stop[d] = s;

if (d == dst) return w;

for (auto [d1, w1, _] : adj[d]) pq.push({d1, w + w1, s + 1});

}

return -1;

}

};

diff --git a/ Problems/1042.cpp b/ Problems/1042.cpp

@@ -0,0 +1,24 @@

class Solution {

public:

vector<int> gardenNoAdj(int n, vector<vector<int>> &paths) {

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

for (auto &p : paths) {

adj[p[0] - 1].push_back(p[1] - 1);

adj[p[1] - 1].push_back(p[0] - 1);

}

vector<int> res(n);

for (int i = 0; i < n; i++) {

bitset<5> colors;

for (int c : adj[i]) colors.set(res[c]);

for (int j = 1; j < 5; j++) {

if (colors[j]) continue;

res[i] = j;

break;

}

}

return res;

}

};

diff --git a/ Problems/1129.cpp b/ Problems/1129.cpp

@@ -0,0 +1,35 @@

class Solution {

typedef vector<vector<int>> ADJ;

public:

vector<int> shortestAlternatingPaths(int n, vector<vector<int>> &redEdges,

vector<vector<int>> &blueEdges) {

vector<vector<int>> dist(2, vector<int>(n, INT_MAX));

vector<ADJ> adj(2, ADJ(n));

queue<pair<int, int>> q;

for (auto &e : redEdges) adj[0][e[0]].push_back(e[1]);

for (auto &e : blueEdges) adj[1][e[0]].push_back(e[1]);

q.push({0, 0});

q.push({0, 1});

dist[0][0] = dist[1][0] = 0;

while (!q.empty()) {

auto [crnt, col] = q.front();

q.pop();

for (int c : adj[!col][crnt]) {

if (dist[!col][c] != INT_MAX) continue;

dist[!col][c] = dist[col][crnt] + 1;

q.push({c, !col});

}

}

vector<int> res(n);

for (int i = 0; i < n; i++) {

res[i] = min(dist[0][i], dist[1][i]);

if (res[i] == INT_MAX) res[i] = -1;

}

return res;

}

};

diff --git a/ Problems/1976.cpp b/ Problems/1976.cpp

@@ -0,0 +1,36 @@

class Solution {

const int MOD = 1e9 + 7;

typedef pair<long long, int> road;

public:

int countPaths(int n, vector<vector<int>> &roads) {

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

for (auto &r : roads) {

adj[r[0]].push_back({r[2], r[1]});

adj[r[1]].push_back({r[2], r[0]});

}

priority_queue<road, vector<road>, greater<road>> pq;

vector<long long> dist(n, LONG_MAX);

vector<int> count(n);

pq.push({0, 0});

count[0] = 1;

dist[0] = 0;

while (!pq.empty()) {

auto [w, e] = pq.top();

pq.pop();

if (w > dist[e]) continue;

for (auto [time, v] : adj[e]) {

if (dist[v] < w + time) continue;

if (dist[v] == w + time) {

count[v] = (count[v] + count[e]) % MOD;

continue;

}

dist[v] = w + time;

count[v] = count[e];

pq.push({dist[v], v});

}

}

return count[n - 1];

}

};

diff --git a/ Problems/2359.cpp b/ Problems/2359.cpp

@@ -0,0 +1,24 @@

class Solution {

public:

int closestMeetingNode(vector<int> &e, int node1, int node2) {

const int n = e.size();

vector<int> d(n, -1);

for (int i = node1, di = 0; i != -1 && d[i] == -1; i = e[i]) d[i] = di++;

int res = -1, mini = INT_MAX;

for (int i = node2, di = 0; i != -1 && d[i] != -2; i = e[i], di++) {

int t = max(d[i], di);

if (d[i] != -1 && t <= mini) {

if (t < mini)

res = i;

else

res = min(res, i);

mini = t;

}

d[i] = -2;

}

return res;

}

};

diff --git a/ Problems/2497.cpp b/ Problems/2497.cpp

@@ -0,0 +1,25 @@

class Solution {

public:

int maxStarSum(vector<int> &vals, vector<vector<int>> &edges, int k) {

vector<vector<int>> adj(vals.size());

for (auto &e : edges) {

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

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

}

int res = INT_MIN;

for (int i = 0; i < vals.size(); i++) {

priority_queue<int, vector<int>, greater<int>> pq;

for (int c : adj[i]) {

if (vals[c] <= 0) continue;

pq.push(vals[c]);

if (pq.size() > k) pq.pop();

}

int sum = vals[i];

while (!pq.empty()) sum += pq.top(), pq.pop();

res = max(res, sum);

}

return res;

}

};

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

@@ -181,6 +181,7 @@ for solving problems. | 0752 | Medium | [Open the Lock](Problems/0752.cpp) | | 0783 | Easy | [Minimum Distance Between BST Nodes](Problems/0783.cpp) | | 0785 | Medium | [Is Graph Bipartite?](Problems/0785.cpp) |

| 0787 | Medium | [Cheapest Flights Within K Stops](Problems/0787.cpp) |

| 0797 | Medium | [All Paths From Source to Target](Problems/0797.cpp) | | 0802 | Medium | [Find Eventual Safe States](Problems/0802.cpp) | | 0830 | Medium | [Kth Smallest Element in a BST](Problems/0230.cpp) |

@@ -213,11 +214,13 @@ for solving problems. | 1022 | Easy | [Sum of Root To Leaf Binary Numbers](Problems/1022.cpp) | | 1026 | Medium | [Maximum Difference Between Node and Ancestor](Problems/1026.cpp) | | 1038 | Medium | [Binary Search Tree to Greater Sum Tree](Problems/1038.cpp) |

| 1042 | Medium | [Flower Planting With No Adjacent](Problems/1042.cpp) |

| 1047 | Easy | [Remove All Adjacent Duplicates In String](Problems/1047.cpp) | | 1051 | Easy | [Height Checker](Problems/1051.cpp) | | 1089 | Easy | [Duplicate Zeros](Problems/1089.cpp) | | 1095 | Easy | [Find Numbers with Even Number of Digits](Problems/1095.cpp) | | 1099 | Easy | [Replace Elements with Greatest Element on Right Side](Problems/1099.cpp) |

| 1129 | Medium | [Shortest Path with Alternating Colors](Problems/1129.cpp) |

| 1137 | Easy | [N-th Tribonacci Number](Problems/1137.cpp) | | 1202 | Medium | [Smallest String With Swaps](Problems/1202.cpp) | | 1209 | Medium | [Remove All Adjacent Duplicates in String II](Problems/1209.cpp) |

@@ -265,6 +268,7 @@ for solving problems. | 1926 | Medium | [Nearest Exit from Entrance in Maze](Problems/1926.cpp) | | 1962 | Medium | [Remove Stones to Minimize the Total](Problems/1962.cpp) | | 1971 | Easy | [Find if Path Exists in Graph](Problems/1971.cpp) |

| 1976 | Medium | [Number of Ways to Arrive at Destination](Problems/1976.cpp) |

| 2039 | Medium | [The Time When the Network Becomes Idle](Problems/2039.cpp) | | 2073 | Easy | [Time Needed to Buy Tickets](Problems/2073.cpp) | | 2095 | Medium | [Delete the Middle Node of a Linked List](Problems/2095.cpp) |

@@ -283,6 +287,7 @@ for solving problems. | 2316 | Medium | [Count Unreachable Pairs of Nodes in an Undirected Graph](Problems/2316.cpp) | | 2326 | Medium | [Spiral Matrix IV](Problems/2326.cpp) | | 2331 | Easy | [Evaluate Boolean Binary Tree](Problems/2331.cpp) |

| 2359 | Medium | [Find Closest Node to Given Two Nodes](Problems/2359.cpp) |

| 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) |

@@ -292,4 +297,5 @@ for solving problems. | 2467 | Medium | [Most Profitable Path in a Tree](Problems/2467.cpp) | | 2477 | Medium | [Minimum Fuel Cost to Report to the Capital](Problems/2477.cpp) | | 2492 | Medium | [Minimum Score of a Path Between Two Cities](Problems/2492.cpp) |

| 2497 | Medium | [Maximum Star Sum of a Graph](Problems/2497.cpp) |