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1D Array

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  • 1. Page 1 of 14 Array Areas Covered on: 1- D ARRAY . Definition of 1-D array. Implementation of 1-D array Basic operations of 1-D array Insertion & Deletion . Searching Sorting . Merging 1-D Array Definations: One dimensional array comprise of finite homogeneous elements represented as: Array name [Lower bound L, Upper bound U] ranges from L through U. To calculate array size (length) =U-L+1 Ex: Ar [-9, 15] Size=15-(-9) +1=23 Implementation of 1-D array: It is done to calculate address of any element in an array. Address of element with subscript I=Base address +ES (I-L) Where ES is size of an array element L is the lower bound of the array. Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 2. Page 2 of 14 Basic operations of 1-D array:--1. Insertion & Deletion 2. Searching 3. Sorting 4. Merging Insertion: placing of new element within the existing array. Insertion is done in two ways: i) If the array is unordered, placing the new element at the end of the array. ii)if the array is sorted then new element is added at appropriate position. Algorithm: 1.ctr=L 2.If LST=U then { Print “Overflow:” Exit from program } 3. if AR[ctr]>ITEM then Pos=1 Else { 4. Repeat steps 5 and 6 until ctr>=U 5. if AR[ctr]<=ITEM and ITEM<=AR[ctr+1] then { Pos=ctr+1 Break } 6. ctr=ctr+1 /*end of repeat here*/ 7. if ctr=U then Pos=U+1 } /*end of if step 3 */ /* shift the element to create space*/ 8. ctr=U 9.while ctr>=pos perform steps 10 through 11 10.AR[ctr+1]=AR[ctr] Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 3. Page 3 of 14 11.ctr=ctr=ctr-1 } 12. AR[pos]=ITEM 13. END Using Function: int FindPos(int AR[],int size,int item) /*to determine the position for element { int pos; if(item<AR[0]) pos=0; else { for(int i=0;i<size-1;i++) { if(AR[i]<=item && item <AR[i+1] { Pos=i+1; Break; } if(i==size-1) pos=size; } return pos; } Deletion: To delete an element from existing array. Algorithm: /*considering that Item’s search in array AR is successful at location pos*/ Two cases arises: Case1: Shifting Upward or left side 1. ctr=pos 2. Repeat steps 3 and 4 until ctr>=U 3. AR [ctr] =AR [ctr-1] 4. ctr=ctr+1 Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 4. Page 4 of 14 /*end of repeat*/ Case II: shifting downwards (or in right side) 1. Ctr=pos 2. Repeat steps 3 and 4 until Ctr<=L 3.AR[ctr]=AR[ctr-1] 4.ctr=ctr-1 /*End of Repeat*/ Searching: Linear search: Linear search method is used to scan the array in a sequential manner.Under this method the whole array is searched one by one until the matching element is obtained . Note: Linear search is done in Unordered array. Algorithm: /*Initialise counter by assigning lower bound value of the array*/ Step1:Set ctr=L (Lower bound=0 in c++) /*Now search for the ITEM*/ Step2: Repeat steps 3 through 4 until ctr>U //Upper Bound(U) is size-1 Step3: if AR [ctr]==ITEM then { Print “search Successful” Print ctr,”is the location of”,ITEM Break } Step 4: ctr=ctr+1 /*End of repeat*/ Step 5 if ctr>U then Print “search Unsuccessful!” Step 6 END Using Function: Int LSearch(int AR[],int size,int item) { For(int i=0;i<size;i++) { Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 5. Page 5 of 14 If(AR[i]==item) return i; } return -1; } Binary search: Steps:To search for ITEM in sorted array (in ascending order) 1. ITEM is compared with middle element of the segment(i.e,in the entire array for the first time). 2.If the ITEM is more than the middle element ,latter part of the segment becomes new segment to be scanned. 3.The same process is repeated for the new segment(s) until the item is found(search successful) or the segment is reduced to the single element and the ITEM is not found(search Unsuccessful). Condition: Array should be in sorted manner Using Function: int Bsearch(int AR[10], int I, int N) { int beg=0, last = N-1,Mid; While(beg<=last) { Mid =(beg+last)/2; If (AR[Mid]==I) Return 1; Else if (I > AR[Mid]) Beg=Mid+1; Else Last=Mid-1; } return 0; } Sorting: Selection Sorting: Steps: Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 6. Page 6 of 14 Pass-1 Find the location LOC of the smallest in the list of n elements. a[1],a[2],……..a[n],then interchange a[loc]with a[1]. Pass-2 Find the location LOC and then interchanged a [LOC] and a [2].since a[1]<=a[2] Pass-3 Find the location LOC of the smallest in the sublist of n-2 elements. a [3],a[4],……a[n], and then interchanged a[LOC] and a[3].Then a[1],a[2]….a[3] is stored, since a[2]<=a[3] --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Pass N-1: Find the location LOC of the smallest of the elements a[n-],a[n] and interchanged a[LOC] and a[n-1].Then: a [1],a[2]….a[n] is strored, since a[n-1]<=a[n] Thus a is sorted after n-1 passes Algorithm: 1. small=AR[L] 2. For i=L to U do { 3. small=AR[i] 4. for J=I to U do { 5. If AR[j]<small then 6. { Small==AR[j] 7. Pos=j } j=j+1; } //In c++ ,0 to size-1 /*end of inner loop*/ /*swap the smallest element with ith element */ 8. temp=AR[i] 9. AR[i]=small 10. AR[pos]=temp } 11. END Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 7. Page 7 of 14 Using Function : Void SelSort(int AR[],int size) { int small, pos,tmp; for(int i=0;i<size;i++) { small=AR[i]; for(int j=i+1;j<size;j++) { if(AR[j]<small) { small=AR[j]; pos=j; } } tmp=AR[i]; AR[i]=AR[pos]; AR[pos]=tmp; cout<<”n Array after pass –“<<i+1<<”—is :”; for(j=0;j<size;j++) cout<<AR[j]<<””; } } Bubble Sort The basic idea of bubble sort is to compare two adjoining values and exchange them if they are not in proper order. Algorithm: 1. For I=L to U 2. { For j=to [(U-1)-I] { Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 8. Page 8 of 14 3. If AR[j]>AR[j+1] then { temp=AR[j] AR[j]=AR[j+1] AR[j+1]=temp } 4. 5. 6. } } 7. END Using Function Void BubbleSort(int AR[],int size) { int tmp,ctr=0; for(int i=0;i<size;i++) { for (int j=0;j<(size-1)-i;j++) { if(AR[j]<AR[j+1]) { tmp=AR[j]; AR[j]=Ar[j+1]; AR[j+1]=tmp; } } cout<<”Array after iteration—“<<++ctr<<”--: “; for(int k=0;k<size;k++) cout<<AR[k]<<””; cout<<endl } } Insertion sorting: Condition: Introduce a sentinel element A [0] = - ∞ (or a very small number) An insertion sort is one that sorts a set of values by inserting values into an existing sorted file. Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 9. Page 9 of 14 The insertion sort algorithm scans array a from a[1] to a[n], inserting each element A[k] into its proper position on the previously sorted subarray a [1],a [2]...a [k1]. Using Function: Void InsSort (int AR [], int size) { int tmp,j; AR [0] =INT_MIN; for (int i=1;i<=size;i++) { tmp=AR[i]; j=i-1; while(tmp<AR[j]) { AR[j+1]=AR[j]; j--; } AR[j+1]=tmp; cout<<”Array after iteration—“<<++ctr<<”--: “; for (int k=0;k<size;k++) cout<<AR[k]<<””; cout<<endl; } } Merging: Merging means combining elements of two arrays to form a new array. Merging in array /* Merging of two array A and B where A is in ascending order ,B is in ascending order and resultant array C will be in Ascending ctr A=L1 ctr B=L2 ctr C=L3 while (ctr A<=U1) &&( ctr B<=U2) { If(A[ctr A]<=B[ctr B]) then Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 10. Page 10 of 14 { C[ctr C]=A[ctr A] ctr C=ctr C + 1 ctr A=ctr A+1 } else { C[ctr C]=B[ctr B] ctr C=ctr C+1 ctr B=ctr B+1 }/*end of while loop If(ctr A >U1) then { While(ctr B <=U2) { C[ctrC]=B[ctr B] ctrC=ctrC+1 ctr B=ctr B+1 } } If(ctr B>U2) then { While (ctr A<=U1) { C[ctr C]=A[ctr A] ctr C=ctr C+1 ctr A=ctr A+1 } } There are some other cases are also possible .These cases are taken place in following situations: 1. When array A[n] is in Acsending order then its control variable ,say ctr A ,should be initialized with array’s lower bound ,which is 0(zero).And the test condition will be ctr<n. 2. When an array ,say A[n] ,is in descending order,then its control variable ,say ctr A ,should be initialized with array’s upper bound,which is n-1. Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 11. Page 11 of 14 Assuming length of array A is M and Length of array B is N-1 . Thus array A has elements A[0] to A[N-1] and B has elements B[0] to B[N-1] .let the resultant array be C with length 10. CtrB=n-1 , ctrA=0 , ctrC=0 while (ctrC<5) do { C[ctrC]=A[ctrA] ctrC=ctrC+1 ctrA=ctrA+1 } while (ctrC<10) do { C[ctrC]=B[ctrB] ctrC=ctrC+1 ctrB=ctrB-1 } ctrC=0 while(ctrC<10) do { print C[ctrC] ctrC= ctrC+1 } END Solved Examples: Q.1 What do you understand by Data Structure. Describe about the types of data structure Ans A data Structure is a named group of data of different data types which can be processed as single unit. There are two types of data structure a. Simple :- i. Array ii. Structure b. Complex i. Linear :- i.Stack ii. Queue iii. Linked-list ii. Non-Linear : Tree Q.2What will be the address of 5th element in a floating point array implemented in C++?The array is specified as amount[16].the base address of the array is 1058. Ans) Standard size of floating-point array=4 bytes 5th element in the array Amount is specified as Amount[4] as the index numbers in c++ starts from 0. Address of Amount[4]=base address +es(I-L) L=0 Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 12. Page 12 of 14 Es=4 Base Address=1058 Putting all these values, Address of Amount[4]=1058+4(4-0)=1074 Q.3 Suppose a one dimentional Array AR containing integers is arranged in ascending order .Write a user defined function in C++ to search for one integer from AR with the help of Binary Search Method , returning an integer 0 to show absence of the number and 1 to show the presence of the number in the array. The function should have three parameters (1. an array AR 2. the number to be searched 3. the number of elements N) Ans. Int Bsearch(int AR[10], int I, int N) { int beg=0, last = N-1,Mid; While(beg<=last) { Mid =(beg+last)/2; If (AR[Mid]==I) Return 1; Else if (I > AR[Mid]) Beg=Mid+1; Else Last=Mid-1; } return 0; } Practice also For Descending order Q.4 Write a function in C++ which accepts an integer array and its size as arguments and exchange the values of first half side element with the second half elements of the array. Example if an array of 10 elements has initial content 12,15,45,23,34,43,77,46,35,47 The resultant array should be like this 43,77,46,35,47,12,15,45,23,34 Ans void swap( int A[ ] ,int size) { int I,j,temp,mid=size/2; if (size %2 = = 0) j=mid ; else j=mid+1; for(i=0;i<mid;i++,j++) { temp= A[i]; Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 13. Page 13 of 14 A[i]=A[j]; A[j]=temp; } } 5. Write an Algorithm for Selection Sort . Ans : 1. small=AR[L] 2. for i= L to U loop 3. { small = AR[i] 4. for j = I to U do 5. { if AR[j] < small then 6. { small = AR[j] 7. pos = j } 8. j = j + 1 } 9. temp = AR[i] 10. AR[i] = small 11. AR[pos] = temp } 12. end Q.6 An algorithm requires two stacks of size M and N that are to be maintained in the memory .Illustrate with an example how will you adjust two stacks in one dimensional array with M+N memory locations so that the overflow condition is minimized . Ans . let us say that the stack A is with size M and Stack B with size N If the stack A is stored in locations 0 to M-1 and the stack B is stored in locations M to M+N-1 ,the separate areas for the two are ensured .in the beginning the tops of the stacks are at opposite ends . when Top A reaches at M-1 , any further insertion will lead to overflow in stack A and when Top B reaches at M. any further insertion in stack B will lead to overflow. Q.7 Given two arrays A and B ,copy last five element of B after first five element of A to create another array C. Assume length of A and B is greater than 5.(Merge Sort) Ans Assuming length of array A is M and Length of array B is N-1 . thus array A has elements A[0] to A[N-1] and B has elements B[0] to B[N-1] .let the resultant array be C with length 10. ctrB=n-1 , ctrA=0 , ctrC=0 while (ctrC<5) do { C[ctrC]=A[ctrA] ctrC=ctrC+1 ctrA=ctrA+1 } while (ctrC<10) do { C[ctrC]=B[ctrB] ctrC=ctrC+1 Prepared By Sumit Kumar Gupta, PGT Computer Science
  • 14. Page 14 of 14 ctrB=ctrB-1 } ctrC=0 while(ctrC<10) do { print C[ctrC] ctrC= ctrC+1 } END | Prepared By Sumit Kumar Gupta, PGT Computer Science