Create Dijsktras Algorithm Usage

Dijsktras Algorithm Usage

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+// C++ program for Dijkstra's single source shortest path
+// algorithm. The program is for adjacency matrix
+// representation of the graph
+#include <iostream>
+using namespace std;
+#include <limits.h>
+
+// Number of vertices in the graph
+#define V 9
+
+// A utility function to find the vertex with minimum
+// distance value, from the set of vertices not yet included
+// in shortest path tree
+int minDistance(int dist[], bool sptSet[])
+{
+
+	// Initialize min value
+	int min = INT_MAX, min_index;
+
+	for (int v = 0; v < V; v++)
+		if (sptSet[v] == false && dist[v] <= min)
+			min = dist[v], min_index = v;
+
+	return min_index;
+}
+
+// A utility function to print the constructed distance
+// array
+void printSolution(int dist[])
+{
+	cout << "Vertex \t Distance from Source" << endl;
+	for (int i = 0; i < V; i++)
+		cout << i << " \t\t\t\t" << dist[i] << endl;
+}
+
+// Function that implements Dijkstra's single source
+// shortest path algorithm for a graph represented using
+// adjacency matrix representation
+void dijkstra(int graph[V][V], int src)
+{
+	int dist[V]; // The output array. dist[i] will hold the
+				// shortest
+	// distance from src to i
+
+	bool sptSet[V]; // sptSet[i] will be true if vertex i is
+					// included in shortest
+	// path tree or shortest distance from src to i is
+	// finalized
+
+	// Initialize all distances as INFINITE and stpSet[] as
+	// false
+	for (int i = 0; i < V; i++)
+		dist[i] = INT_MAX, sptSet[i] = false;
+
+	// Distance of source vertex from itself is always 0
+	dist[src] = 0;
+
+	// Find shortest path for all vertices
+	for (int count = 0; count < V - 1; count++) {
+		// Pick the minimum distance vertex from the set of
+		// vertices not yet processed. u is always equal to
+		// src in the first iteration.
+		int u = minDistance(dist, sptSet);
+
+		// Mark the picked vertex as processed
+		sptSet[u] = true;
+
+		// Update dist value of the adjacent vertices of the
+		// picked vertex.
+		for (int v = 0; v < V; v++)
+
+			// Update dist[v] only if is not in sptSet,
+			// there is an edge from u to v, and total
+			// weight of path from src to v through u is
+			// smaller than current value of dist[v]
+			if (!sptSet[v] && graph[u][v]
+				&& dist[u] != INT_MAX
+				&& dist[u] + graph[u][v] < dist[v])
+				dist[v] = dist[u] + graph[u][v];
+	}
+
+	// print the constructed distance array
+	printSolution(dist);
+}
+
+// driver's code
+int main()
+{
+
+	/* Let us create the example graph discussed above */
+	int graph[V][V] = { { 0, 4, 0, 0, 0, 0, 0, 8, 0 },
+						{ 4, 0, 8, 0, 0, 0, 0, 11, 0 },
+						{ 0, 8, 0, 7, 0, 4, 0, 0, 2 },
+						{ 0, 0, 7, 0, 9, 14, 0, 0, 0 },
+						{ 0, 0, 0, 9, 0, 10, 0, 0, 0 },
+						{ 0, 0, 4, 14, 10, 0, 2, 0, 0 },
+						{ 0, 0, 0, 0, 0, 2, 0, 1, 6 },
+						{ 8, 11, 0, 0, 0, 0, 1, 0, 7 },
+						{ 0, 0, 2, 0, 0, 0, 6, 7, 0 } };
+
+	// Function call
+	dijkstra(graph, 0);
+
+	return 0;
+}
+
+// This code is contributed by shivanisinghss2110

Find Subarray with given sum

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+/* A simple program to print subarray
+with sum as given sum */
+#include <bits/stdc++.h>
+using namespace std;
+
+/* Returns true if the there is a subarray
+of arr[] with sum equal to 'sum' otherwise
+returns false. Also, prints the result */
+void subArraySum(int arr[], int n, int sum)
+{
+
+	// Pick a starting point
+	for (int i = 0; i < n; i++) {
+		int currentSum = arr[i];
+
+		if (currentSum == sum) {
+			cout << "Sum found at indexes " << i << endl;
+			return;
+		}
+		else {
+			// Try all subarrays starting with 'i'
+			for (int j = i + 1; j < n; j++) {
+				currentSum += arr[j];
+
+				if (currentSum == sum) {
+					cout << "Sum found between indexes "
+						<< i << " and " << j << endl;
+					return;
+				}
+			}
+		}
+	}
+	cout << "No subarray found";
+	return;
+}
+
+// Driver Code
+int main()
+{
+	int arr[] = { 15, 2, 4, 8, 9, 5, 10, 23 };
+	int n = sizeof(arr) / sizeof(arr[0]);
+	int sum = 23;
+	subArraySum(arr, n, sum);
+	return 0;
+}
+
+// This code is contributed
+// by rathbhupendra

Sort an array of 0s, 1s and 2s

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+// C++ program to sort an array
+// with 0, 1 and 2 in a single pass
+#include <bits/stdc++.h>
+using namespace std;
+
+// Function to sort the input array,
+// the array is assumed
+// to have values in {0, 1, 2}
+void sort012(int a[], int arr_size)
+{
+	int lo = 0;
+	int hi = arr_size - 1;
+	int mid = 0;
+
+	// Iterate till all the elements
+	// are sorted
+	while (mid <= hi) {
+		switch (a[mid]) {
+
+		// If the element is 0
+		case 0:
+			swap(a[lo++], a[mid++]);
+			break;
+
+		// If the element is 1 .
+		case 1:
+			mid++;
+			break;
+
+		// If the element is 2
+		case 2:
+			swap(a[mid], a[hi--]);
+			break;
+		}
+	}
+}
+
+// Function to print array arr[]
+void printArray(int arr[], int arr_size)
+{
+	// Iterate and print every element
+	for (int i = 0; i < arr_size; i++)
+		cout << arr[i] << " ";
+}
+
+// Driver Code
+int main()
+{
+	int arr[] = { 0, 1, 1, 0, 1, 2, 1, 2, 0, 0, 0, 1 };
+	int n = sizeof(arr) / sizeof(arr[0]);
+
+	sort012(arr, n);
+
+	printArray(arr, n);
+
+	return 0;
+}
+
+// This code is contributed by Shivi_Aggarwal

Write a program to reverse an array or string

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+// Iterative C++ program to reverse an array 
+#include <bits/stdc++.h> 
+using namespace std; 
+
+/* Function to reverse arr[] from start to end*/
+void rvereseArray(int arr[], int start, int end) 
+{ 
+	while (start < end) 
+	{ 
+		int temp = arr[start]; 
+		arr[start] = arr[end]; 
+		arr[end] = temp; 
+		start++; 
+		end--; 
+	} 
+}	 
+
+/* Utility function to print an array */
+void printArray(int arr[], int size) 
+{ 
+for (int i = 0; i < size; i++) 
+cout << arr[i] << " "; 
+
+cout << endl; 
+} 
+
+/* Driver function to test above functions */
+int main() 
+{ 
+	int arr[] = {1, 2, 3, 4, 5, 6}; 
+
+	int n = sizeof(arr) / sizeof(arr[0]); 
+
+	// To print original array 
+	printArray(arr, n); 
+
+	// Function calling 
+	rvereseArray(arr, 0, n-1); 
+
+	cout << "Reversed array is" << endl; 
+
+	// To print the Reversed array 
+	printArray(arr, n); 
+
+	return 0; 
+}