399. Evaluate Division | GRAPHS | | LeetCode Daily Challenge POTD

[@dianamujahed3600]

thank you very much

[@bkmeher9005]

Superb explanation bhai ... thanks

[@orzAR26]

Thanks bro, you are the one making me consistent to do leetcode ❤

[@shikharshukla8836]

thanks

[@salmankhader1258]

Your videos are helping me a lot. nice explanation keep going!

[@deepcodes]

class Solution { public: unordered_map adjList; vectorans; bool dfs(string dividend, string divisor, unordered_setvis, double currProd) { if (vis.find(dividend) != vis.end()) { return false; } vis.insert(dividend); if (dividend == divisor) { ans.push_back(currProd); return true; } bool found = false; for (auto ne : adjList[dividend]) { found = dfs(ne.first, divisor, vis, currProd*ne.second); if (found) { return true; } } return false; } vector calcEquation(vector& equations, vector& values, vector& queries) { int n = equations.size(), m = queries.size(); adjList.clear(); ans.clear(); for (int i = 0; i < n ; i++) { string dividend = equations[i][0]; string divisor = equations[i][1]; adjList[dividend].push_back({divisor, values[i]}); adjList[divisor].push_back({dividend, 1.0 / values[i]}); } for (auto &q : queries) { string dividend = q[0]; string divisor = q[1]; if (adjList.find(dividend) == adjList.end() || adjList.find(divisor) == adjList.end()) { ans.push_back(-1.0); } else { unordered_setvis; if (!dfs(dividend, divisor, vis, 1.0)) { ans.push_back(-1); } } } return ans; } };

[@peakpotential9]

Why are we using map, can't we use vector instead?

[@deepcodes]

Nodes are string, not int. If you want to access value in vector in O(1) then you pass integer index. But here, indexing is done on nodes that are string values.