added parenthesis_matching.c in c folder

C/finding_duplicates.c

@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void finding_and_counting_duplicates_in_sorted_array(int A[],int n)
+{
+    int i,j;
+    for(i=0;i<n-1;i++)
+    {
+        if(A[i]==A[i+1])
+        {
+            j=i+1;
+            while(A[j]==A[i]) j++;
+            printf("%d is appearing %d times \n", A[i],j-i);
+            i=j-1;
+        }
+    }
+}
+
+void finding_and_counting_duplicates_in_sortedorunsorted_array_using_hashing(int A[],int H[],int n,int h)
+{
+    int i;
+    for(i=0;i<n;i++)   //for storing count in hashtable
+        H[A[i]]++;
+
+    for(i=0;i<=h;i++)
+    {
+        if(H[i]>1)
+            printf("%d is repeated %d times \n",i,H[i]);
+    }
+}
+
+void finding_and_counting_duplicates_in_unsorted_array(int A[],int n)
+{
+    int count,i,j;
+    for (i=0;i<n-1;i++)
+    {
+        count =1;
+        if(A[i]!= -1)
+        {
+            for(j=i+1;j<n;j++)
+            {
+                if(A[i]==A[j])
+                {
+                    count ++;
+                    A[j]=-1;
+                }
+            }
+        }
+        if(count >1)
+            printf("%d is appearing %d times\n",A[i],count);
+    }
+}
+
+int main()
+{
+    int A[10]={3,2,2,7,10,16,12,15,15,20};
+    int n = 10,h=20;
+    int H[21]={0};
+    //finding_and_counting_duplicates_in_sortedorunsorted_array_using_hashing(A,H,n,h);
+    finding_and_counting_duplicates_in_unsorted_array(A,n);
+    return 0;
+}

C/parenthesis_matching.c

@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct Node
+{
+    char data;
+    struct Node *next;
+}*top=NULL;
+
+void push(char x)
+{
+    struct Node *t;
+    t=(struct Node*)malloc(sizeof(struct Node));
+    if(t==NULL)
+        printf("Stack is Full");
+    else
+    {
+        t->data=x;
+        t->next=top;
+        top=t;
+    }
+}
+
+char pop()
+{
+    struct Node *t;
+    char x=-1;
+
+    if(top==NULL)
+        printf("Stack is Empty\n");
+    else
+    {
+        t=top;
+        top=top->next;
+        x=t->data;
+        free(t);
+    }
+    return x;
+}
+
+
+void Display()
+{
+    struct Node *p;
+    p=top;
+    while(p!=NULL)
+    {
+        printf("%d ",p->data);
+        p=p->data;
+    }
+    printf("\n");
+}
+
+int isBalanced(char *exp)
+{
+    int i;
+    for(i=0;exp[i]!='\0';i++)
+    {
+        if(exp[i]=='(')
+            push(exp[i]);
+        else if(exp[i]==')')
+        {
+            if(top==NULL)
+                return 0;
+            pop();
+        }
+    }
+    if(top==NULL)
+        return 1;
+    else
+        return 0;
+}
+
+int main()
+{
+    char *exp="(((a+b)*(c-d))";
+    printf("%d ",isBalanced(exp));
+    return 0;
+}