alr

.gitignore

@@ -0,0 +1,3 @@
+*.class
+mergeSort.java
+kruskal.java

floydWarshall.java

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+import java.util.*;

galeShapley.java

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+import java.util.*;
+
+public class galeShapley {
+
+    static int N;
+
+    static int womanCharToIndex(char ch) {
+        return ch - 'W';
+    }
+
+    static int manCharToIndex(char ch) {
+        return ch - 'A';
+    }
+
+    static boolean prefers(int[][] womenPref, int w, int m, int m1) {
+        for (int i = 0; i < N; i++) {
+            if (womenPref[w][i] == m)
+                return true;
+
+            if (womenPref[w][i] == m1)
+                return false;
+        }
+        return false;
+    }
+
+    static void galeShapley(int[][] womenPref, int[][] menPref) {
+
+        int[] womenPartner = new int[N];
+        boolean[] menFree = new boolean[N];
+        int[] nextProposal = new int[N];
+
+        Arrays.fill(womenPartner, -1);
+        Arrays.fill(menFree, true);
+
+        int freeCount = N;
+
+        while (freeCount > 0) {
+
+            int m = -1;
+
+            for (int i = 0; i < N; i++) {
+                if (menFree[i] && nextProposal[i] < N) {
+                    m = i;
+                    break;
+                }
+            }
+
+            if (m == -1)
+                break;
+
+            int w = menPref[m][nextProposal[m]];
+            nextProposal[m]++;
+
+            if (womenPartner[w] == -1) {
+                womenPartner[w] = m;
+                menFree[m] = false;
+                freeCount--;
+            } else {
+
+                int m1 = womenPartner[w];
+
+                if (prefers(womenPref, w, m, m1)) {
+                    womenPartner[w] = m;
+                    menFree[m] = false;
+                    menFree[m1] = true;
+                }
+            }
+        }
+
+        System.out.println("\nStable matching result:");
+
+        for (int i = 0; i < N; i++) {
+            System.out.println(
+                "Woman " + (char)('W' + i) +
+                " is matched with Man " + (char)('A' + womenPartner[i])
+            );
+        }
+    }
+
+    public static void main(String[] args) {
+
+        Scanner sc = new Scanner(System.in);
+
+        System.out.print("Enter number of pairs (n): ");
+        N = sc.nextInt();
+
+        int[][] menPref = new int[N][N];
+        int[][] womenPref = new int[N][N];
+
+        System.out.println("\nEnter Men's Preference Lists:");
+
+        for (int i = 0; i < N; i++) {
+
+            System.out.println("Preferences of Man " + (char)('A' + i) + ":");
+
+            for (int j = 0; j < N; j++) {
+                char ch = sc.next().charAt(0);
+                menPref[i][j] = womanCharToIndex(ch);
+            }
+        }
+
+        System.out.println("\nEnter Women's Preference Lists:");
+
+        for (int i = 0; i < N; i++) {
+
+            System.out.println("Preferences of Woman " + (char)('W' + i) + ":");
+
+            for (int j = 0; j < N; j++) {
+                char ch = sc.next().charAt(0);
+                womenPref[i][j] = manCharToIndex(ch);
+            }
+        }
+
+        galeShapley(womenPref, menPref);
+
+        sc.close();
+    }
+}

horsePool.java

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+import java.util.*;
+public class horsePool{
+    static HashMap<Character, Integer> shift = new HashMap<>();
+    static void shiftTable(String pattern){
+        for(char ch = 'A'; ch<='Z';ch++)
+            shift.put(ch, pattern.length());
+        shift.put(' ', pattern.length());
+        for(int i =0;i<pattern.length()-1;i++)
+            shift.put(pattern.charAt(i), pattern.length()-1-i);
+    }
+
+    static int search(String text, String pattern){
+        int n = text.length();
+        int m = pattern.length();
+
+        int i = m-1;
+        while(i<n){
+            int k = 0;
+            while(k<m && pattern.charAt(m-1-k)== text.charAt(i-k)){
+                k++;
+                
+            }
+            if(k==m){
+                return i-m+1;
+            }
+            i+=shift.getOrDefault(text.charAt(i), m);
+        }
+        return -1;
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.print("\nEnter text: ");
+        String text = sc.nextLine().toUpperCase();
+
+        System.out.print("\nENter pattern: ");
+        String pattern = sc.nextLine().toUpperCase();
+
+        shiftTable(pattern);
+        int pos = search(text, pattern);
+        if(pos!=-1){
+            System.out.println("Pattern found at index "+ pos);
+
+        }else{
+            System.out.println("Pattern not found");
+        }
+        sc.close();
+
+    }
+
+}

kruskalMST.java

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+import java.util.*;
+public class kruskalMST{
+    static class Edge implements Comparable<Edge>{
+        int u,v,weight;
+        Edge(int u, int v, int weight){
+            this.u=u;
+            this.v = v;
+            this.weight = weight;
+
+        }
+        public int compareTo(Edge other){
+            return this.weight-other.weight;
+        }
+    }
+    static int[] parent;
+
+    static int find(int x){
+        if(parent[x]!=x)
+            parent[x] = find(parent[x]);
+        return parent[x];
+    }
+
+    static void union(int x, int y){
+       int  rootX = find(x);
+        int rootY = find(y);
+
+        parent[rootY]= rootX;
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.print("ENter number of vertices: ");
+        int N  = sc.nextInt();
+
+        int[][] graph = new int[N][N];
+
+        System.out.println("\nEnter adjacency matrix(0 if no edge): ");
+        for(int i =0;i<N;i++){
+            for(int j =0;j<N;j++){
+                graph[i][j] = sc.nextInt();
+            }
+        }
+        List<Edge> edges = new ArrayList<>();
+        for(int i =0;i<N;i++){
+            for(int j =i+1;j<N;j++){
+                if(graph[i][j]!=0)
+                    edges.add(new Edge(i,j,graph[i][j]));
+            }
+        }
+        Collections.sort(edges);
+
+        parent = new int[N];
+        for(int i = 0;i<N;i++){
+            parent[i]= i;
+
+        }
+        int totalCost = 0;
+        int edgeCount = 0;
+
+        System.out.println("\nEdges in MST:");
+        for(Edge e : edges){
+            int rootU = find(e.u);
+            int rootV = find(e.v);
+            if(rootU!=rootV){
+                System.out.println(e.u+" - "+e.v+" : "+e.weight);
+                totalCost+=e.weight;
+                union(rootU,rootV);
+                edgeCount++;
+
+                if(edgeCount == N-1)
+                    break;
+
+            }
+        }
+        System.out.print("\ntotal minimum cost: "+totalCost);
+        sc.close();
+        
+
+
+
+    }
+}

mergeSort.java

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+import java.util.*;
+public class mergeSort{
+    static void merge(int arr[], int left, int mid, int right, int temp[]){
+        int i = left;
+        int j = mid+1;
+        int k = left;
+
+        while(i<=mid && j<=right){
+            if(arr[i]<=arr[j]){
+                temp[k++] = arr[i++];
+            }else{
+                temp[k++] = arr[j++];
+            }
+        }
+        while(i<=mid)
+            temp[k++] = arr[i++];
+        while(j<=right)
+            temp[k++] = arr[j++];
+
+        for(int x = left;x<=right;x++){
+            arr[x] = temp[x];
+        }
+    }
+    static void mergeSort(int arr[], int left, int right, int temp[]){
+        if(left<right){
+            int mid = (right+left)/2;
+            mergeSort(arr, left, mid, temp);
+            mergeSort(arr, mid+1, right, temp);
+            merge(arr, left, mid, right, temp);
+        }
+    }
+
+    public static void main(String[] args){
+        Scanner sc =  new Scanner(System.in);
+
+        System.out.print("Enter number of elements: ");
+        int n= sc.nextInt();
+
+        int arr[] = new int[n];
+        int temp[] = new int[n];
+
+        System.out.println("Enter "+n+" elements: ");
+        for(int i =0;i<n;i++){
+            arr[i] = sc.nextInt();
+        }
+        mergeSort(arr,0,n-1,temp);
+        System.out.println("\nSorted array:");
+        for(int i =0;i<n;i++){
+            System.out.print(arr[i]+ " ");
+        }
+        sc.close();
+    }
+}

primMST.java

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+import java.util.*;
+public class primMST{
+    static int N;
+    static int[][] graph;
+    static void primMST(){
+        int[] key = new int[N];
+        boolean[] mstSet = new boolean[N];
+        int[] parent = new int[N];
+
+        Arrays.fill(key, Integer.MAX_VALUE);
+        key[0] = 0;
+        parent[0]=-1;
+        for(int count =0;count<N-1;count++){
+            int u =-1;
+            int min = Integer.MAX_VALUE;
+            for(int i =0;i<N;i++){
+                if(!mstSet[i] && key[i]<min){
+                    min = key[i];
+                    u = i;
+                
+            }
+        }
+        mstSet[u] = true;
+        for(int v = 0;v<N;v++){
+            if(!mstSet[v] && graph[u][v]!=0 && graph[u][v]<key[v]){
+                key[v] = graph[u][v];
+                parent[v] = u;
+
+            }
+        }
+        
+    }
+    int totalCost = 0;
+    System.out.println("\nEdges in MST:");
+    for(int i =1;i<N;i++){
+        System.out.println(parent[i]+" - "+i+" : "+graph[i][parent[i]]);
+        totalCost+=graph[i][parent[i]];
+    }
+    System.out.println("Total minimum cost: "+totalCost);
+
+}
+public static void main(String[] args){
+    Scanner sc = new Scanner(System.in);
+    System.out.print("ENter number of vertices:");
+    N = sc.nextInt();
+
+    graph= new int[N][N];
+
+    System.out.println("ENter adjacency matrix(0 if no edges): ");
+    for(int i =0;i<N;i++){
+        for(int j=0;j<N;j++){
+            graph[i][j] = sc.nextInt();
+        }
+    }
+    primMST();
+    sc.close();
+}
+}

quickSort.java

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+import java.util.*;
+public class quickSort{
+    static int partition(int[] arr, int low, int high){
+        int pivot = arr[low];
+        int i = low+1;
+        int j = high;
+        while(i<=j){
+            while(i<=high && arr[i]<=pivot)
+                i++;
+            while(arr[j]>pivot)
+                j--;
+            if(i<j){
+                int temp=arr[i];
+                arr[i]=arr[j];
+                arr[j]=temp;
+            }
+        }
+        int temp = arr[j];
+        arr[j]=arr[low];
+        arr[low] = temp;
+
+        return j ;
+    }
+
+    static void quickSort(int[] arr, int low, int high){
+        if(low<high){
+            int pi = partition(arr, low,high);
+            quickSort(arr, low, pi-1);
+            quickSort(arr, pi+1, high);
+
+        }
+    }
+    public static void main(String[] args){
+        Scanner sc  = new Scanner(System.in);
+        System.out.print("\nENter number of products: ");
+        int n = sc.nextInt();
+
+        int[] prices = new int[n];
+        System.out.println("ENter product prices: ");
+        for(int i =0;i<n;i++){
+            prices[i] = sc.nextInt();
+        }
+        long startTime = System.nanoTime();
+        quickSort(prices, 0 ,n-1);
+
+        long endTime = System.nanoTime();
+
+        System.out.println("\nSOrted prices list: ");
+        for(int i =0;i<n;i++){
+            System.out.print(prices[i]+ " ");
+
+        }
+        long execTime = endTime - startTime;
+        System.out.println("\nExecution time: "+ execTime+" nanoseconds");
+        sc.close();
+    }
+}

topologicalSort.java

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+import java.util.*;
+
+public class topologicalSort{
+    static int N;
+    static int[][] graph;
+    static boolean[] visited;
+    static Stack<Integer> stack = new Stack<>();
+
+    static void dfs(int v){
+        visited[v] = true;
+        for(int i =0;i<N;i++){
+            if(!visited[i] && graph[v][i]==1){
+                dfs(i);
+            }
+        }
+        stack.push(v);
+    }
+
+    static void topoSort(){
+        for(int i=0;i<N;i++){
+            if(!visited[i]){
+                dfs(i);
+        }
+    }
+
+    System.out.println("\nValid execution order");
+    while(!stack.isEmpty()){
+        System.out.print((char)('A'+ stack.pop())+"->");
+    }
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.print("\nEnter number of tasks: ");
+        N = sc.nextInt();
+        graph = new int[N][N];
+        visited = new boolean[N];
+
+        System.out.print("ENter number of dependencies: ");
+        int edges = sc.nextInt();
+
+        System.out.println("Enter dependencies (u v means u -> v):");
+        for(int i = 0;i<edges;i++){
+            char u = sc.next().charAt(0);
+            char v = sc.next().charAt(0);
+
+            graph[u-'A'][v-'A'] = 1;
+        }
+        topoSort();
+        sc.close();
+    
+    }
+    
+}