From 32f86afd250940132e24d4942f125fe2ca8f54a4 Mon Sep 17 00:00:00 2001
From: Pratyay Banerjee <48355572+Neilblaze@users.noreply.github.com>
Date: Fri, 11 Oct 2019 11:51:45 +0530
Subject: [PATCH 1/2] Update Contributors.md

---
 Contributors.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Contributors.md b/Contributors.md
index 9c826ec..bd65f5f 100644
--- a/Contributors.md
+++ b/Contributors.md
@@ -14,4 +14,4 @@
 12. [Hacker-set](https://github.com/Hacker-set)]
 13. [Prateek Sengar]https://github.com/prtksengar3)
 14. [ANant Rungta](https://github.com/Anant016)
-
+15. [Pratyay Banerjee](https://github.com/Neilblaze)

From fb6639c75e84ea346221dd625f55fac96a90ca49 Mon Sep 17 00:00:00 2001
From: Pratyay Banerjee <48355572+Neilblaze@users.noreply.github.com>
Date: Fri, 11 Oct 2019 11:57:09 +0530
Subject: [PATCH 2/2] Create Next_permutation.cpp

---
 Next_permutation.cpp | 54 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Next_permutation.cpp

diff --git a/Next_permutation.cpp b/Next_permutation.cpp
new file mode 100644
index 0000000..959da04
--- /dev/null
+++ b/Next_permutation.cpp
@@ -0,0 +1,54 @@
+/**
+ *  Implement next permutation algorithm. i.e
+ *  Given a word w, rearrange the letters of w to construct another word s in such a way that
+ *  s is lexicographically greater than w.
+ *  In case of multiple possible answers, find the lexicographically smallest one.
+ *  Example:
+ *  ab --> ba
+ *  bb --> bb
+ *  hefg --> hegf
+ *  dhck --> dhkc
+ *  dkhc --> hcdk
+ */
+
+#include <iostream>
+
+std::string
+next_permutation( std::string str)
+{
+  int len = str.length();
+  int i = len -1;
+  // We will iterate string from end, and once we have encountered a pair of letters
+  // such that str[i] < str[i-1] , i-1 would become our pivot
+  while( i > 0 && str[i] <= str[i-1] ) {
+    --i;
+  }
+  if ( i == 0 ) {
+    return str;
+  }
+  //our pivot right now would be str[i-1]
+  int j = len - 1;
+  while( j >= i && str[j] <= str[i-1] ) {
+    --j;
+  }
+  std::swap(str[i-1], str[j]);
+  j = len - 1;
+  //reverse the suffix
+  while( i < j ) {
+    std::swap(str[i], str[j]);
+    --j;
+    ++i;
+  }
+  return str;
+}
+
+int main()
+{
+  std::string str, str_next;
+  std::cout << "Enter a string : ";
+  std::cin >> str;
+  str_next = next_permutation(str);
+  std::cout << "Next permutation of " << str << " is "
+            << str_next << std::endl;
+  return 0;
+}