// 547. Number of Provinces #include "leetcode.h" /* * dthere are 'n' cities. some of them are connected, while some are not. if * city 'a' is connected directly with city 'b', and city 'b' is connected * directly with city 'c', then city 'a' is connected indirectly with city 'c'. * a province is a group of directly or indirectly connected cities and no other * cities outside of the group. given an 'n x n' matrix 'is_connected' where * 'is_connected[i][j] = 1' if the i'th city and the j'th city are directly * connected, and 'is_connected[i][j] = 0' otherwise. return the total number of * provinces */ class Solution { void dfs(int i, vvd(int) & is_connected, vector &vis) { vis[i] = true; for (int j = 0; j < vis.size(); j++) if (i != j && is_connected[i][j] && !vis[j]) dfs(j, is_connected, vis); } public: int findCircleNum(vvd(int) & is_connected) { if (is_connected.empty()) return 0; int n = is_connected.size(), groups = 0; vector vis(n, false); for (int i = 0; i < vis.size(); i++) groups += !vis[i] ? dfs(i, is_connected, vis), 1 : 0; return groups; } }; int main() { Solution obj; vvd(int) ic1 = {{1, 1, 0}, {1, 1, 0}, {0, 0, 1}}; vvd(int) ic2 = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}; printf("%d\n", obj.findCircleNum(ic1)); // expect: 2 printf("%d\n", obj.findCircleNum(ic2)); // expect: 3 }