Add cpp code for day 38 stack (#256)

* cpp code for day 7 and 8

* cpp code for day 7 and 8

* fixed readme merge conflict

* added cpp code for day 38

Co-authored-by: MADHAV BAHL <madhavbahl10@gmail.com>

Author: profgrammer

day38/C++/profgrammer_stack.cpp

@@ -0,0 +1,54 @@
+/*
+  * @author profgrammer
+  * @date 17-2-2019
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+class MyStack{
+  private:
+    int top;
+    int stack[100];
+    int size;
+  public:
+    MyStack(int _size){
+      top = -1;
+      size = _size;
+    }
+
+    bool isEmpty(){
+      return top == -1;
+    }
+
+    bool isFull(){
+      return top == size - 1;
+    }
+
+    int peek(){
+      if(isEmpty()) {cout<<"Stack empty..\n"; return -1;}
+      return stack[top];
+    }
+
+    void push(int x){
+      if(isFull()) cout<<"Stack full..\n";
+      else stack[++top] = x;
+    }
+
+    void pop(){
+      if(isEmpty()) cout<<"Stack empty..\n";
+      else top--;
+    }
+};
+
+int main(){
+  MyStack stack(2);
+  stack.push(1);
+  stack.push(2);
+  stack.push(3); // err
+  cout<<stack.peek()<<endl;
+  stack.pop();
+  stack.pop();
+  stack.pop(); // err
+  cout<<stack.peek()<<endl;
+}

day38/README.md

@@ -278,4 +278,65 @@ public class Stack {
         while(c==1);
     }
 }
-```
+```
+
+## C++ Implementation
+
+### [Solution by @profgrammer](./C++/profgrammer_stack.cpp)
+
+```cpp
+/*
+  * @author profgrammer
+  * @date 17-2-2019
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+class MyStack{
+  private:
+    int top;
+    int stack[100];
+    int size;
+  public:
+    MyStack(int _size){
+      top = -1;
+      size = _size;
+    }
+
+    bool isEmpty(){
+      return top == -1;
+    }
+
+    bool isFull(){
+      return top == size - 1;
+    }
+
+    int peek(){
+      if(isEmpty()) {cout<<"Stack empty..\n"; return -1;}
+      return stack[top];
+    }
+
+    void push(int x){
+      if(isFull()) cout<<"Stack full..\n";
+      else stack[++top] = x;
+    }
+
+    void pop(){
+      if(isEmpty()) cout<<"Stack empty..\n";
+      else top--;
+    }
+};
+
+int main(){
+  MyStack stack(2);
+  stack.push(1);
+  stack.push(2);
+  stack.push(3); // err
+  cout<<stack.peek()<<endl;
+  stack.pop();
+  stack.pop();
+  stack.pop(); // err
+  cout<<stack.peek()<<endl;
+}
+```

day8/README.md

@@ -200,6 +200,55 @@ int main() {
 }
 ```
 
+
+=======
+### [Solution 2 by @profgrammer](./Cpp/profgrammer_editdistance.cpp)
+```cpp
+/*
+  *@author: profgrammer
+  *@date: 31-12-2018
+*/
+
+#include <bits/stdc++.h>
+#define inf 100000000
+using namespace std;
+
+string s1, s2;
+
+int dp[1500][1500];
+
+// function that returns minimum edits required to convert s1[0 .. i-1] into s2[0 .. j-1]
+int minEdit(int i, int j){
+  // base cases. if s1 finishes we need j insertions, if s2 finishes we need i insertions
+  if(i == 0) return j;
+  if(j == 0) return i;
+  // housekeeping for dp with memoisation
+  if(dp[i][j] != inf) return dp[i][j];
+  // if the last characters are the same, no need to change anything and move both pointers by 1 unit
+  if(s1[i-1] == s2[j-1]) {
+    return dp[i][j] = minEdit(i-1, j-1);
+  }
+  // replace s1[i] to be s2[j]. the strings to be checked are still s1[0 .. i-1] and s2[0 .. j-1] but the cost is +1
+  int minReplace = 1 + minEdit(i-1, j-1);
+  // delete s1[i], cost is +1 and the strings are now s1[0 .. i-1] and s2[0 .. j] because we need to compare the i-1th character with the jth character
+  int minDelete = 1 + minEdit(i-1, j); 
+  // insert a character into s1 at index i. cost is +1 and now the strings to be checked are s1[0 .. i] because the ith character isn't compared yet and s2[0 .. j-1]
+  int minInsert = 1 + minEdit(i, j-1);
+  // return min of these 3 values
+  return dp[i][j] = min(minReplace, min(minDelete, minInsert));
+}
+
+int main() {
+  for(int i = 0;i < 1500;i++){
+    for(int j = 0;j < 1500;j++) dp[i][j] = inf;
+  }
+  cin>>s1>>s2;
+  cout<<"The minimum edit distance is: ";
+  cout<<minEdit(s1.size(), s2.size())<<endl;
+}
+```
+
+
 ### [Solution 3 by @divyakhetan](./Cpp/EditDistanceday8.cpp)
 
 ```cpp
@@ -249,6 +298,7 @@ int main(){
 
 ### [Solution 4 by @aaditkamat] (./C++/levenshtein_distance.cpp)
 
+
 ```cpp
 /**
  * @author: aaditkamat
@@ -291,6 +341,7 @@ int main() {
     }
 ```
 
+
 ### C Implementation
 
 ### [Solution 1](./C/levenshtein_distance.c)