Graph

src/DistributeWaterInVillage.java

@@ -0,0 +1,44 @@
+import java.util.*;
+public class DistributeWaterInVillage {
+    static int[] parent;
+    static int minCostToSupplyWater(int n, int[] wells, int[][] pipes) {
+        parent = new int[n + 1];
+        for (int i = 1; i <= n; i++) {
+            parent[i] = i;
+        }
+        List<int[]> edges = new ArrayList<>();
+        for (int[] pipe : pipes) {
+            edges.add(pipe);
+        }
+        for (int i = 1; i <= n; i++) {
+            edges.add(new int[] {0, i, wells[i - 1]});
+        }
+        int result = 0;
+        Collections.sort(edges, (a, b) -> a[2] - b[2]);
+        for (int[] edge : edges) {
+            int x = edge[0];
+            int y = edge[1];
+
+            int px = find(x);
+            int py = find(y);
+
+            if (px != py) {
+                result += edge[2];
+                parent[py] = px;
+            }
+        }
+        return result;
+    }
+    static int find(int x) {
+        if (parent[x] != x) parent[x] = find(parent[x]);
+        return parent[x];
+    }
+
+    public static void main(String[] args) {
+        int n = 3;
+        int[] wells = {1,2,2};
+        int[][] pipes = {{1,2,1},{2,3,1}};
+
+        System.out.println("Minimum Cost To Supply water: "+ minCostToSupplyWater(n, wells, pipes));
+    }
+}

src/FindCelebrity.java

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+public class FindCelebrity {
+    static int[][] graph;
+    static boolean knows(int a, int b) {
+        return graph[a][b] == 1;
+    }
+    static int findCelebrity(int n) {
+        int[] in = new int[n];
+        for (int i = 0; i < n; i++) {
+            for (int j = i + 1; j < n; j++) {
+                if (knows(i, j)) {
+                    in[i]--;
+                    in[j]++;
+                }
+                if (knows(j, i)) {
+                    in[j]--;
+                    in[i]++;
+                }
+            }
+        }
+
+        for (int i = 0; i < n; i++) {
+            if (in[i] == n - 1) return i;
+        }
+
+        return -1;
+    }
+
+    public static void main(String[] args) {
+        graph = new int[][] {
+                {1, 1, 0},
+                {0, 1, 0},
+                {1, 1, 1}
+        };
+        int celebrity = findCelebrity(graph.length);
+        if (celebrity == -1) {
+            System.out.println("No celebrity found.");
+        } else {
+            System.out.println("Celebrity is person: " + celebrity);
+        }
+    }
+}