StringReverseUsingStack.cpp

Reverses the given string using Stack Data Structure. This solves rathoresrikant#576

StringReverseUsingStack.cpp

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+#include <bits/stdc++.h> 
+using namespace std; 
+
+//to represent a stack 
+class Stack 
+{ 
+	public: 
+	int top; 
+	unsigned capacity; 
+	char* array; 
+}; 
+
+// function to create a stack of given 
+// capacity. It initializes size of stack as 0 
+Stack* createStack(unsigned capacity) 
+{ 
+	Stack* stack = new Stack(); 
+	stack->capacity = capacity; 
+	stack->top = -1; 
+	stack->array = new char[(stack->capacity * sizeof(char))]; 
+	return stack; 
+} 
+
+// Stack is full when top is equal to the last index 
+int isFull(Stack* stack) 
+{ return stack->top == stack->capacity - 1; } 
+
+// Stack is empty when top is equal to -1 
+int isEmpty(Stack* stack) 
+{ return stack->top == -1; } 
+
+// Function to add an item to stack. 
+// It increases top by 1 
+void push(Stack* stack, char item) 
+{ 
+	if (isFull(stack)) 
+		return; 
+	stack->array[++stack->top] = item; 
+} 
+
+// Function to remove an item from stack. 
+// It decreases top by 1 
+char pop(Stack* stack) 
+{ 
+	if (isEmpty(stack)) 
+		return -1; 
+	return stack->array[stack->top--]; 
+} 
+
+// A stack based function to reverse a string 
+void reverse(char str[]) 
+{ 
+	// Create a stack of capacity 
+	//equal to length of string 
+	int n = strlen(str); 
+	Stack* stack = createStack(n); 
+
+	// Push all characters of string to stack 
+	int i; 
+	for (i = 0; i < n; i++) 
+		push(stack, str[i]); 
+
+	// Pop all characters of string and 
+	// put them back to str 
+	for (i = 0; i < n; i++) 
+		str[i] = pop(stack); 
+} 
+
+// Driver code 
+int main() 
+{ 
+	char str[] = "Reverse Me"; 
+
+	reverse(str); 
+	cout << "Reversed string is " << str; 
+
+	return 0; 
+}