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-rw-r--r--number_provinces.cpp41
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+// 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<bool> &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<bool> 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
+}