From f0eaafe857a98f5a86b58a293a68afc74a49104d Mon Sep 17 00:00:00 2001
From: harshbhagwani94 <39380791+harshbhagwani94@users.noreply.github.com>
Date: Sat, 10 Nov 2018 16:47:17 +0530
Subject: [PATCH] Added IITR Flipkart 2018

---
 smallestRestrictedPalindrome.cpp | 35 ++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 smallestRestrictedPalindrome.cpp

diff --git a/smallestRestrictedPalindrome.cpp b/smallestRestrictedPalindrome.cpp
new file mode 100644
index 0000000..b9d45db
--- /dev/null
+++ b/smallestRestrictedPalindrome.cpp
@@ -0,0 +1,35 @@
+/*
+IITR Flipkart 2018
+
+Given a string s, return a string t satisfying the following:
+1. s contains t
+2. t is a palindrome
+3. t is largest possible
+If multiple t exists, return the lexicographically smallest t.
+
+1 <= |s| <= 100000
+
+O(|s| + 26)
+*/
+string smallestRestrictedPalindrome(string s) {
+	int c[26] = {};
+	for (char ch : s) c[ch - 'a']++;
+	string t = "";
+	for (int i = 0; i < 26; i++) {
+		for (int j = c[i] >> 1; j--; ) {
+			t += (char)('a' + i);
+		}
+	}
+	int fl = 0;
+	for (int i = 0; not fl and i < 26; i++) {
+		if (c[i] & 1) {
+			t += (char)('a' + i);
+			fl = 1;
+		}
+	}
+	int n = t.size() - fl;
+	for (int i = n; i--; ) {
+		t += t[i];
+	}
+	return t;
+}