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-rw-r--r--find_centre_star_graph.c34
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diff --git a/find_centre_star_graph.c b/find_centre_star_graph.c
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+// 1791. Find Center of Star Graph
+#include "leetcode.h"
+
+/*
+ * there is an undirected star graph consisting of 'n' nodes labeled from 1 to
+ * 'n'. a star graph is a graph where there is one centre node and exactly 'n -
+ * 1' edges that connect the centre node with every other node. you are given a
+ * 2d integer array 'edges' where 'edges[i] = [ui, vi]' indicates that there is
+ * an edge between the node 'ui' and 'vi'. return the centre of the star graph.
+ */
+
+int findCenter(int **edges, int edgesSize, int *edgesColSize) {
+ int centre = 0, col = 0, candidate = edges[0][col], n = 0;
+ for (int i = 0; i < edgesSize; i++) {
+ for (int j = 0; j < edgesColSize[i]; j++)
+ if (candidate == edges[i][j]) {
+ centre = edges[i][j];
+ n++;
+ }
+ if (i == edgesSize - 1 && n < edgesSize) {
+ i = 0;
+ candidate = edges[0][col + 1];
+ }
+ }
+ return centre;
+}
+
+int main() {
+ int e1[3][2] = {{1, 2}, {2, 3}, {4, 2}},
+ e2[4][2] = {{1, 2}, {5, 1}, {1, 3}, {1, 4}};
+ int ecs1 = 3, ecs2 = 4;
+ printf("%d\n", findCenter((int **)e1, ARRAY_SIZE(e1), &ecs1)); // expect: 2
+ printf("%d\n", findCenter((int **)e2, ARRAY_SIZE(e2), &ecs2)); // expect: 1
+}