Added codes for 23 Feb

GeeksForGeeks/February/23-2-24/GFG.java

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+//{ Driver Code Starts
+import java.io.*;
+import java.util.*;
+
+
+class IntArray
+{
+    public static int[] input(BufferedReader br, int n) throws IOException
+    {
+        String[] s = br.readLine().trim().split(" ");
+        int[] a = new int[n];
+        for(int i = 0; i < n; i++)
+            a[i] = Integer.parseInt(s[i]);
+
+        return a;
+    }
+
+    public static void print(int[] a)
+    {
+        for(int e : a)
+            System.out.print(e + " ");
+        System.out.println();
+    }
+
+    public static void print(ArrayList<Integer> a)
+    {
+        for(int e : a)
+            System.out.print(e + " ");
+        System.out.println();
+    }
+}
+
+class GFG {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int t;
+        t = Integer.parseInt(br.readLine().trim());
+        while(t-- > 0){
+
+            int n; 
+            n = Integer.parseInt(br.readLine().trim());
+
+
+            int[] price = IntArray.input(br, n);
+
+            Solution obj = new Solution();
+            int res = obj.maxProfit(n, price);
+
+            System.out.println(res);
+
+        }
+    }
+}
+
+// } Driver Code Ends
+
+
+class Solution 
+{
+    public static int maxProfit(int n, int[] price) 
+    {
+        // code here
+        int first_buy = Integer.MIN_VALUE;
+        int first_sell = 0;
+        int second_buy = Integer.MIN_VALUE;
+        int second_sell = 0;
+
+        for(int i = 0; i < n; i++) 
+        {
+            first_buy = Math.max(first_buy, -price[i]); 
+            first_sell = Math.max(first_sell, first_buy + price[i]); 
+            second_buy = Math.max(second_buy, first_sell - price[i]);
+            second_sell = Math.max(second_sell, second_buy + price[i]);
+        }
+
+        return second_sell;
+    }
+}

GeeksForGeeks/February/23-2-24/README.md

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+Time complexity - O(n)
+Space complexity - O(1)

LeetCode/February/23-2-24/README.md

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+Time complexity - O((v + e) * logv)
+Space complexity - O(v+e)

LeetCode/February/23-2-24/Solution.java

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+class Solution 
+{
+    public int findCheapestPrice(int n, int[][] flights, int src, int dst, int k) 
+    {
+        List<Pair<Integer, Integer>>[] graph = new List[n];
+
+        for (int i = 0; i < n; i++)
+            graph[i] = new ArrayList<>();
+
+        for (int[] flight : flights) 
+        {
+            int u = flight[0];
+            int v = flight[1];
+            int w = flight[2];
+            graph[u].add(new Pair<>(v, w));
+        }
+
+        return dijkstra(graph, src, dst, k);
+    }
+
+    private int dijkstra(List<Pair<Integer, Integer>>[] graph, int src, int dst, int k) 
+    {
+        int[][] dist = new int[graph.length][k + 2];
+        Arrays.stream(dist).forEach(A -> Arrays.fill(A, Integer.MAX_VALUE));
+        // (d, u, stops)
+        Queue<int[]> minHeap = new PriorityQueue<>((a, b) -> a[0] - b[0]);
+
+        dist[src][k + 1] = 0;
+        minHeap.offer(new int[] {dist[src][k + 1], src, k + 1});
+
+        while (!minHeap.isEmpty()) 
+        {
+            int d = minHeap.peek()[0];
+            int u = minHeap.peek()[1];
+            int stops = minHeap.poll()[2];
+
+            if (u == dst)
+                return d;
+            if (stops == 0)
+                continue;
+
+            for (Pair<Integer, Integer> pair : graph[u]) 
+            {
+                int v = pair.getKey();
+                int w = pair.getValue();
+
+                if (d + w < dist[v][stops - 1]) 
+                {
+                    dist[v][stops - 1] = d + w;
+                    minHeap.offer(new int[] {dist[v][stops - 1], v, stops - 1});
+                }
+            }
+        }
+
+        return -1;
+    }
+}