Merge pull request #40 from Yash-Bandal/main

Added the potd October 16 With DryRun

october_2024/potd_16_10_2024.cpp

@@ -0,0 +1,106 @@
+//1405. Longest Happy String
+
+#include <iostream>
+#include <queue>
+#include <string>
+using namespace std;
+
+class Solution {
+public:
+    string longestDiverseString(int a, int b, int c) {
+        priority_queue<pair<int, char>> pq;
+
+        // Push in pq pairs of count and character
+        if (a > 0) {
+            pq.push({a, 'a'}); // Example input: a = 1, b = 1, c = 7
+        }
+        if (b > 0) {
+            pq.push({b, 'b'});
+        }
+        if (c > 0) {
+            pq.push({c, 'c'});
+        }
+
+        // Don't declare vector<string> silly mistake
+        string res = "";
+
+        // Dry run starts here
+        /*
+        Initial priority queue state:
+        pq = [(7, 'c'), (1, 'a'), (1, 'b')]
+
+        Result string starts as empty: res = ""
+        */
+
+        while (!pq.empty()) {
+            auto [count1, char1] = pq.top(); // Get the character with the highest count
+            pq.pop();
+
+            // Check the 'three same characters constraint'
+            //                               last                    second last
+            if (res.size() >= 2 && res.back() == char1 && res[res.size() - 2] == char1) {
+                // Condition is met, so we can't add char1
+                if (pq.empty()) {
+                    break; // No other characters available
+                }
+                // Take next most frequent character
+                auto [count2, char2] = pq.top(); // Get the second most frequent character
+                pq.pop();
+
+                res += char2; // Add char2 to the result
+                count2--;     // Decrement its count
+
+                // Check if we can push char2 back into the queue
+                if (count2 > 0) {
+                    pq.push({count2, char2});
+                }
+
+                // Push char1 back into the queue as well
+                pq.push({count1, char1});
+            } else {
+                // If adding char1 is okay
+                res += char1; // Add char1 to the result
+                count1--;     // Decrement its count
+
+                // Push char1 back if there's still some left
+                if (count1 > 0) {
+                    pq.push({count1, char1});
+                }
+            }
+        }
+
+        return res; // Final result will be "ccaccbcc" or similar valid output
+    }
+};
+// Dry run example updates:
+/*
+1st iteration:
+count1 = 7, char1 = 'c', res = "c"
+count1 decremented to 6. pq = [(6, 'c'), (1, 'a'), (1, 'b')]
+
+2nd iteration:
+count1 = 6, char1 = 'c', res = "cc" (not allowed)
+count2 = 1, char2 = 'a', res = "cca", count2 decremented to 0. pq = [(6, 'c'),
+(1, 'b')]
+
+3rd iteration:
+count1 = 6, char1 = 'c', res = "ccac"
+count1 decremented to 5. pq = [(5, 'c'), (1, 'b')]
+
+4th iteration:
+count1 = 5, char1 = 'c', res = "ccaca" (not allowed)
+count2 = 1, char2 = 'b', res = "ccacb", count2 decremented to 0. pq = [(5, 'c')]
+
+5th iteration:
+count1 = 5, char1 = 'c', res = "ccacbc"
+count1 decremented to 4. pq = [(4, 'c')]
+
+6th iteration:
+count1 = 4, char1 = 'c', res = "ccacbcc"
+count1 decremented to 3. pq = [(3, 'c')]
+
+7th iteration:
+count1 = 3, char1 = 'c', res = "ccacbcc"
+...
+Continue until the priority queue is empty.
+*/