Solution for linked list reversal problem.

linked_list_cycle/solutions/cycleInLinkedList.c

@@ -0,0 +1,79 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct sll_int_node
+{
+	int iData;
+	struct sll_int_node *pNextNode;
+} sll_int_node;
+
+/* Allocates a node and sets its parameters */
+void createNewIntNode_Sll(sll_int_node **ppNewNode, int iData, sll_int_node *pNextNode)
+{
+	*ppNewNode = (sll_int_node *)malloc(sizeof(sll_int_node));
+	(*ppNewNode)->iData = iData;
+	(*ppNewNode)->pNextNode = pNextNode;
+}
+
+void printList_Sll(sll_int_node *pHead)
+{
+	while(pHead != NULL)
+	{
+		printf("%d ", pHead->iData);
+		pHead = pHead->pNextNode;
+	}
+}
+
+/* Insert to the start of the list */
+void insertFrontIntNode_Sll(sll_int_node **ppHead, int iNewData)
+{
+	sll_int_node *pNewNode = NULL;
+
+	createNewIntNode_Sll(&pNewNode, iNewData, *ppHead);
+
+	*ppHead = pNewNode;
+}
+
+bool detectLoop_Sll(sll_int_node *pHead)
+{
+	sll_int_node *pSlow = pHead;
+	sll_int_node *pFast = pHead;
+
+	if(pHead != NULL)
+	{
+		while((pFast->pNextNode != NULL) && (pFast->pNextNode->pNextNode != NULL))
+		{
+			pSlow = pSlow->pNextNode;
+			pFast = pFast->pNextNode->pNextNode;
+
+			if(pSlow == pFast)
+				return true;
+		}
+	}
+	else
+		printf("ERR(detectLoop): List is empty\n");
+
+	return false;
+}
+
+int main(void)
+{
+	sll_int_node *head = NULL;
+
+	insertFrontIntNode_Sll(&head, 1);
+	insertFrontIntNode_Sll(&head, 2);
+	insertFrontIntNode_Sll(&head, 3);
+	insertFrontIntNode_Sll(&head, 4);
+	insertFrontIntNode_Sll(&head, 5);
+
+	/* Before inserting loop */
+	printf("List contains loop: %s\n", detectLoop_Sll(head) ? "true" : "false");
+
+	head->pNextNode->pNextNode->pNextNode->pNextNode->pNextNode = head->pNextNode->pNextNode;
+
+	/* After inserting loop */
+	printf("List contains loop: %s\n", detectLoop_Sll(head) ? "true" : "false");
+
+	return 0;
+}

linked_list_reverse/solutions/reverseLinkedList.c

@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct
+{
+	int iData;
+	struct sll_int_node *pNextNode;
+} sll_int_node;
+
+void reverseList_Iter_Sll(sll_int_node **ppHead)
+{
+	sll_int_node *pPrev = NULL;
+	sll_int_node *pCurr = *ppHead;
+	sll_int_node *pNext = NULL;
+
+	if(*ppHead != NULL)
+	{
+		while(pCurr != NULL)
+		{
+			pNext = pCurr->pNextNode;
+			pCurr->pNextNode = pPrev;
+
+			pPrev = pCurr;
+			pCurr = pNext;
+		}
+
+		*ppHead = pPrev;
+	}
+	else
+		printf("ERR(reverseList_Iter_Sll): List is empty\n");
+}
+
+sll_int_node * reverseSubList_Sll(sll_int_node *pPrev, sll_int_node *pCurr)
+{
+	sll_int_node *pNewHead;
+
+	if(pCurr->pNextNode == NULL)
+	{
+		pCurr->pNextNode = pPrev;
+		return pCurr;
+	}
+
+	pNewHead = reverseSubList_Sll(pCurr, pCurr->pNextNode);
+	pCurr->pNextNode = pPrev;
+
+	return pNewHead;
+}
+
+void reverseList_Recur_Sll(sll_int_node **ppHead)
+{
+	if(*ppHead != NULL)
+	{
+		*ppHead = reverseSubList_Sll(NULL, *ppHead);
+	}
+	else
+		printf("ERR(reverseList_Recur_Sll): List is empty\n");
+}
+
+/* Allocates a node and sets its parameters */
+void createNewIntNode_Sll(sll_int_node **ppNewNode, int iData, sll_int_node *pNextNode)
+{
+	*ppNewNode = (sll_int_node *)malloc(sizeof(sll_int_node));
+	(*ppNewNode)->iData = iData;
+	(*ppNewNode)->pNextNode = pNextNode;
+}
+
+void printList_Sll(sll_int_node *pHead)
+{
+	while(pHead != NULL)
+	{
+		printf("%d ", pHead->iData);
+		pHead = pHead->pNextNode;
+	}
+}
+
+/* Insert to the start of the list */
+void insertFrontIntNode_Sll(sll_int_node **ppHead, int iNewData)
+{
+	sll_int_node *pNewNode = NULL;
+
+	createNewIntNode_Sll(&pNewNode, iNewData, *ppHead);
+
+	*ppHead = pNewNode;
+}
+
+int main(void)
+{
+	sll_int_node *head1 = NULL, *head2 = NULL;
+
+	insertFrontIntNode_Sll(&head1, 1);
+	insertFrontIntNode_Sll(&head1, 2);
+	insertFrontIntNode_Sll(&head1, 3);
+	insertFrontIntNode_Sll(&head1, 4);
+
+	insertFrontIntNode_Sll(&head2, -1);
+	insertFrontIntNode_Sll(&head2, -2);
+	insertFrontIntNode_Sll(&head2, -3);
+	insertFrontIntNode_Sll(&head2, -4);
+
+	printf("List1: ");
+	printList_Sll(head1);
+	printf("\n");
+
+	reverseList_Iter_Sll(&head1);
+	printf("Reversed List1 (Iterative): ");
+	printList_Sll(head1);
+	printf("\n");
+
+	printf("List2: ");
+	printList_Sll(head2);
+	printf("\n");
+
+	reverseList_Recur_Sll(&head2);
+	printf("Reversed List2 (Iterative): ");
+	printList_Sll(head2);
+	printf("\n");
+
+	return 0;
+}

minimum_stack/solutions/minStack.c

@@ -0,0 +1,125 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct stacknode_int
+{
+	int iData;
+	struct stacknode_int *pNextNode;
+} stacknode_int;
+
+typedef struct
+{
+	stacknode_int *pOrigStackTop;
+	stacknode_int *pMinStackTop;
+} minStackNode_int;
+
+/* Allocates a node and sets its parameters */
+static void createNewStackNode_Int(stacknode_int **ppNewNode, int iData, stacknode_int *pNextNode)
+{
+	*ppNewNode = (stacknode_int *)malloc(sizeof(stacknode_int));
+	(*ppNewNode)->iData = iData;
+	(*ppNewNode)->pNextNode = pNextNode;
+}
+
+bool isStackEmpty(stacknode_int *pTop)
+{
+	return (pTop == NULL);
+}
+
+bool peekFromStack(stacknode_int *pTop, int *ipData)
+{
+	if(isStackEmpty(pTop))
+	{
+		printf("ERR(Trying to peek): Stack Empty!\n");
+		return false;
+	}
+
+	*ipData = pTop->iData;
+
+	return true;
+}
+
+void printStack(stacknode_int *pTop)
+{
+	while(pTop != NULL)
+	{
+		printf("%d ", pTop->iData);
+		pTop = pTop->pNextNode;
+	}
+}
+
+void pushToMinStack(minStackNode_int *pStack, int iNewData)
+{
+	stacknode_int *pNewNode = NULL;
+	int iMinStackData = 0;
+
+	createNewStackNode_Int(&pNewNode, iNewData, (pStack->pOrigStackTop));
+	pStack->pOrigStackTop = pNewNode;
+
+	if(!isStackEmpty(pStack->pMinStackTop) && (iNewData > (pStack->pMinStackTop->iData)))
+		iMinStackData = pStack->pMinStackTop->iData;
+	else
+		iMinStackData = iNewData;
+
+	createNewStackNode_Int(&pNewNode, iMinStackData, (pStack->pMinStackTop));
+	pStack->pMinStackTop = pNewNode;
+}
+
+bool popFromMinStack(minStackNode_int *pStack, int *ipPoppedData)
+{
+	stacknode_int *pOldTop = NULL;
+
+	if(isStackEmpty(pStack->pOrigStackTop))
+	{
+		printf("ERR(Trying to pop): Stack Underflow!\n");
+		return false;
+	}
+
+	pOldTop = pStack->pMinStackTop;
+	pStack->pMinStackTop = pOldTop->pNextNode;
+	free(pOldTop);
+
+	pOldTop = pStack->pOrigStackTop;
+	*ipPoppedData = pOldTop->iData;
+	pStack->pOrigStackTop = pOldTop->pNextNode;
+	free(pOldTop);
+
+	return true;
+}
+
+bool getMinFromMinStack(minStackNode_int *pStack, int *ipPeekedData)
+{
+	return peekFromStack(pStack->pMinStackTop, ipPeekedData);
+}
+
+int main(void)
+{
+	minStackNode_int s;
+	int iMin = 0, iDummy = 0;
+
+	s.pMinStackTop = NULL;
+	s.pOrigStackTop = NULL;
+
+	pushToMinStack(&s, 15);
+	pushToMinStack(&s, 20);
+	pushToMinStack(&s, 10);
+
+	getMinFromMinStack(&s, &iMin);
+	printf("Stack content: ");
+	printStack(s.pOrigStackTop);
+	printf("\tMin: %d\n", iMin);
+
+	pushToMinStack(&s, 5);
+	getMinFromMinStack(&s, &iMin);
+	printf("Stack content: ");
+	printStack(s.pOrigStackTop);
+	printf("\tMin: %d\n", iMin);
+
+	popFromMinStack(&s, &iDummy);
+	popFromMinStack(&s, &iDummy);
+	getMinFromMinStack(&s, &iMin);
+	printf("Stack content: ");
+	printStack(s.pOrigStackTop);
+	printf("\t\tMin: %d\n", iMin);
+}

target_sum/solutions/TargetSumPair.java

@@ -0,0 +1,33 @@
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class TargetSumPair
+{
+	public static boolean checkForSumPair(int[] iArr, int iSum)
+	{
+		if(iArr.length >= 2)
+		{
+			Set<Integer> set = new HashSet<Integer>();
+
+			set.add(iArr[0]);
+			for(int i = 1; i < iArr.length; i++)
+			{
+				if(set.contains(iSum - iArr[i]))
+					return true;
+
+				set.add(iArr[i]);
+			}
+		}
+		return false;
+	}
+
+	public static void main (String[] args) throws java.lang.Exception
+	{
+		int[] iArrTest1 = {5, 3, 4, 2, 8, -1, 15};
+		int[] iArrTest2 = {3, 4, 5};
+
+		System.out.println("Test1-> " + checkForSumPair(iArrTest1, 13));
+		System.out.println("Test2-> " + checkForSumPair(iArrTest2, 13));
+	}
+}