From 08d87b4399b39b16250629bbe673ca9886e6be7f Mon Sep 17 00:00:00 2001
From: Sandhya Mishra <102294639+Sandhyamishra18@users.noreply.github.com>
Date: Tue, 18 Oct 2022 16:38:01 +0530
Subject: [PATCH] Remove Duplicate Letters stack cpp solution

Remove Duplicate Letters stack cpp easy  solution
Name : Sandhya Mishra
Github Id : https://github.com/Sandhyamishra18
---
 C++/Stack/Remove Duplicate Letters cpp | 27 ++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 C++/Stack/Remove Duplicate Letters cpp

diff --git a/C++/Stack/Remove Duplicate Letters cpp b/C++/Stack/Remove Duplicate Letters cpp
new file mode 100644
index 0000000..ff90310
--- /dev/null
+++ b/C++/Stack/Remove Duplicate Letters cpp	
@@ -0,0 +1,27 @@
+ 
+string solve(string s){
+string res;
+stack<char> stk;
+set<char> present;
+map<char,int>last;
+for(int i=0;i<s.size();i++){
+    last[s[i]]=i;
+}
+for(int i=0;i<s.size();i++){
+    if(present.find(s[i])!=present.end()){
+        continue;
+    }
+    while(!stk.empty() && stk.top()>s[i] && last[stk.top()]>i){
+        present.erase(stk.top());
+        stk.pop();
+    }
+    stk.push(s[i]);
+    present.insert(s[i]);
+}
+while(!stk.empty()){
+    res+=stk.top();
+    stk.pop();
+}
+reverse(res.begin(),res.end());
+return res;
+}