Added code for Dijkstra Algorithm in C++

Dijsktra.cpp

@@ -0,0 +1,170 @@
+#include <iostream>
+#include <algorithm>
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Dijsktra {
+private:
+	int **matrix;
+	int size, source, dest;
+	int *min_dis;
+	bool *fixed;
+
+public:
+	void input() {
+		cout << "Enter size" << endl;
+		cin >> size;
+
+		initialize();
+		make_adj_mat();
+
+		cout << "Enter source and destination:" << endl;
+		cin >> source >> dest;
+	}
+
+	void calc_shortest(int point) {
+		fixed[point] = true;
+
+		if(point == dest) return;
+
+		else {
+			if(point == source) min_dis[point] = 0;
+
+			for (int i = 0; i < size; ++i) {
+				if (matrix[point][i] != 0 && !fixed[i]) {
+					if (min_dis[i] != -1){
+						min_dis[i] = min(min_dis[i], min_dis[point] + matrix[point][i]);
+					}
+					else {
+						min_dis[i] = min_dis[point] + matrix[point][i];
+					}
+				}
+
+			}
+			point = get_next();
+			calc_shortest(point);
+
+		}
+
+	}
+
+	int get_next() {
+		int min = 9999;
+		int point = -1;
+		for (int i = 0; i < size; ++i) {
+			if (!fixed[i] && min_dis[i] != -1) {
+				if (min_dis[i] < min ) {
+					min = min_dis[i];
+					point = i;
+				}
+			}
+		}
+		return point;
+	}
+
+	void make_adj_mat() {
+		for (int i = 0; i < size; i++) {
+			cout << "Enter connections of node " << i <<
+			" (vert, weight). Put -1 at end." << endl;
+
+			while(1) {
+				int vert, weight;
+				cin >> vert;
+				if (vert == -1) break;
+
+				cin >> weight;
+				matrix[i][vert] = weight;
+			}
+		}
+	}
+
+	void initialize() {
+		min_dis = new int[size];
+		for (int i = 0; i < size; i++){
+			min_dis[i] = -1;
+		}
+
+		fixed = new bool[10];
+		for (int i = 0; i < size; ++i){
+			fixed[i] = false;
+		}
+
+		matrix = new int *[size];
+		for (int i = 0; i < size; i++){
+			matrix[i] = new int[10];
+		}
+
+		for(int i = 0; i < size; i++) {
+			for(int j = 0; j < size; j++) {
+				matrix[i][j] = 0;
+			}
+		}
+	}
+
+	void print_min() {
+		for (int i = 0; i < size; ++i) {
+			cout << "Min dis of " << i << 
+			" from source is " << min_dis[i] << endl;
+		}
+	}
+
+	void print_mat() {
+		for(int i = 0; i < size; i++) {
+			for(int j = 0; j < size; j++) {
+				cout << matrix[i][j] << "\t";
+			}
+			cout << endl;
+		}
+	}
+
+	void print_path() {
+		stack<int> path;
+		int point = dest;
+
+		path.push(point);
+		while(point != source) {
+			for (int i = 0; i < size; ++i){
+				int inter_pt_dis = matrix[i][point];
+				if (inter_pt_dis != 0 && min_dis[i] + inter_pt_dis == min_dis[point]){
+					point = i;
+					path.push(point);	
+					break;
+				}
+			}
+		}
+		while(!path.empty()) {
+			cout << path.top() << "  ";
+			path.pop();
+		}
+		cout << endl;
+	}
+
+	int get_source() {
+		return source;
+	}
+
+	~Dijsktra() {
+		delete(matrix);
+	}
+
+};
+
+int main() {
+	Dijsktra dijsktra;
+	dijsktra.input();
+
+	cout << "\nThe adjacency matrix is:" << endl;
+	dijsktra.print_mat();
+
+	dijsktra.calc_shortest(dijsktra.get_source());
+
+	cout << "\nThe minimum distaces:" << endl;
+	dijsktra.print_min();
+
+	cout << "\nThe path is:" << endl;
+	dijsktra.print_path();
+
+	return 0;
+}