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search_algorithm.c
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#include<stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
int ascending; //1 if array is sorted in ascending order, 0 if descending
int key; //the key to be searched for, in the array
int matched_index = -1 ; //index of the matched key
typedef enum {
LessThan = 0,
LessThanEquals = 1,
Equals = 2,
GreaterThanEquals = 3,
GreaterThan = 4
} SearchType;
typedef enum {
NotFound,
FoundExact,
FoundGreater,
FoundLess
} SearchResult;
SearchType type;
SearchResult result;
//generating the strings for the enums
const char* getTypeString(SearchType type)
{
switch(type){
case LessThan: return "LessThan";
case LessThanEquals: return "LessThanEquals";
case Equals: return "Equals";
case GreaterThanEquals: return"GreaterThanEquals";
case GreaterThan: return "GreaterThan";
}
}
const char* getResultString(SearchResult result)
{
switch(result){
case NotFound: return "NotFound";
case FoundExact: return "FoundExact";
case FoundGreater: return "FoundGreater";
case FoundLess: return "FoundLess";
}
}
SearchResult Search(
const int * const items,
const int n_items,
const int ascending,
const int key,
const SearchType type,
int* const index)
{
int i,j,lessflag=0, equalstoflag=0,greaterthanflag=0;
matched_index = -1;
switch(type)
{
////////////////////// Equals Case ///////////////////////
case Equals:{
for(i=0;i<n_items;i++){
if(key ==*(items+i))
{
equalstoflag++;
matched_index=i;
break;
}
else continue;
}
if(equalstoflag == 0)
return NotFound;
else
return FoundExact;
}
//////////////////// Greater Than Case //////////////////
case GreaterThan:
{
if(ascending!=0)
{
if(key >= items[n_items-1]) //Checking if key is >= last element in an ascending array
{
greaterthanflag=2;
matched_index = -1 ;
}
else
{
for(i=0;i<n_items-1;i++)
{
if(key >= *(items+i) && key < *(items+i+1))
{
greaterthanflag++;
matched_index = i+1;
break;
}
else continue;
}
if(greaterthanflag == 0)
{
greaterthanflag = 1;
matched_index = 0;
}
}
}
// checking descending array below
else
{
if(key >= *(items+0))
{
greaterthanflag=2;
matched_index = -1;
}
else if(key < items[n_items-1])
{
greaterthanflag++;
matched_index = n_items-1;
}
else{
for(i=1;i<n_items;i++)
{
if(key >= *(items+i) && key < *(items+i-1))
{
greaterthanflag++;
matched_index = i-1;
break;
}
else continue;
}
}
}
//printf("%d",greaterthanflag);
if (greaterthanflag==2) return NotFound;
else return FoundGreater;
}
///////////////// GreaterThanEquals Case /////////////////
case GreaterThanEquals:{
equalstoflag=0, greaterthanflag=0;
//checking equals case below
for(i=0;i<n_items;i++)
{
if(key==*(items+i))
{
equalstoflag++;
matched_index = i;
break;
}
else continue;
}
if(ascending!=0)
{
//checking greater than case below
if(key>*(items+n_items-1)) // checking last element of acending array
greaterthanflag=0;
else
{
for(i=0;i<n_items-1;i++)
{ if (key < items[0]) {
greaterthanflag++;
matched_index=0;
}
else if(key >= *(items+i) && key < *(items+i+1))
{
if(equalstoflag == 1)
{
return FoundExact;
}
greaterthanflag++;
matched_index=i+1;
break;
}
else continue;
}
}
}
// checking descending array below
else
{
if(key>*(items+0))
{ greaterthanflag=0;
matched_index = -1;
}
else if (key < items[n_items-1])
{
greaterthanflag++;
matched_index = n_items-1;
}
else{
for(i=1;i<n_items;i++)
{
if(key > *(items+i) && key < *(items+i-1))
{
greaterthanflag++;
matched_index=i-1;
break;
}
else continue;
}
}
}
if (equalstoflag!=0)
return FoundExact;
else if(greaterthanflag!=0)
return FoundGreater;
else
return NotFound;
}
///////////////////// Less Than Case ///////////////////////
case LessThan:
{
if(ascending!=0)
{
if(key < *(items+0)) //checking if first element is less than key
{
lessflag=0;
}
else if(key > items[n_items-1]){
lessflag++;
matched_index = n_items - 1;
}
else
{
for(i=0;i<n_items;i++){
if(key <= *(items+i) && key > *(items+i-1))
{
lessflag++;
matched_index = i-1;
break;
}
else continue;
}
}
}
// checking descending array below
else
{
if(key < *(items+n_items-1))
{
lessflag=0;
matched_index = -1;
}
else if(key > items[0])
{
lessflag++;
matched_index = 0;
}
else
{
for(i=0;i<n_items-1;i++)
{
if(key <= *(items+i) && key > *(items+i+1))
{
lessflag++;
matched_index = i+1;
break;
}
else continue;
}
}
}
if (lessflag==0)
return NotFound;
else
return FoundLess;
}
//////////////////// Less Than Equals Case ///////////////////
case LessThanEquals:{
equalstoflag=0,
lessflag=0;
// checking equals to key condition below
for(i=0;i<n_items;i++)
{
if(key == *(items+i))
{
equalstoflag++;
matched_index = i;
//printf("%d\n",matched_index );
if (equalstoflag!=0)
return FoundExact;
break;
}
else continue;
}
if(ascending!=0)
{
// checking less than key condition below
if(key<*(items+0))
{
lessflag=0;
}
else if (key > items[n_items-1])
{
lessflag++;
matched_index = n_items-1;
}
else
{
for(i=1;i<n_items;i++)
{
if(key < *(items+i) && key > *(items+i-1))
{
lessflag++;
matched_index = i-1;
//printf("%d\n",matched_index );
break;
}
else continue;
}
}
}
//check for descending array
else
{
if(key<*(items+n_items-1))
{
lessflag=0;
matched_index = -1 ;
}
else if(key>items[0])
{
lessflag++;
matched_index = 0;
}
else
{
for(i=0;i<n_items-1;i++)
{
if(key <= *(items+i) && key > *(items+i+1))
{
lessflag++;
matched_index = i+1;
break;
}
else continue;
}
}
}
if (equalstoflag!=0)
return FoundExact;
else if(lessflag!=0)
return FoundLess;
else
return NotFound;
}
}
}
static void test_ascending()
{
//_____________ Test Cases for Ascending Array___________________//
printf("\n\nTesting Ascending array [0,2,4,6,8]\n");
printf("+-----+-------------------+--------------+-------+ \n | Key | Type | Returns | Index | \n+-----+-------------------+--------------+-------+\n");
int items_ascending[] ={0,2,4,6,8};
result = Search(items_ascending,5,1,key=-1,type=LessThanEquals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=0,type=LessThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=0,type=Equals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=1,type=Equals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=2,type=GreaterThanEquals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=2,type=GreaterThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=-1,type=GreaterThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items_ascending,5,1,key=10,type=LessThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
}
static void test_descending()
{
//__________________Test cases for Descending array__________________//
printf("\n\nTesting Descending array [8,6,4,2,0]\n");
printf("+-----+-------------------+--------------+-------+ \n | Key | Type | Returns | Index | \n+-----+-------------------+--------------+-------+\n");
int items[] ={8,6,4,2,0};
result = Search(items,5,0,key=-1,type=LessThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=4,type=LessThanEquals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=8,type=Equals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=5,type=GreaterThanEquals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=2,type=GreaterThanEquals,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=9,type=GreaterThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=10,type=LessThan,&matched_index);
printf(" %d %s %s %d\n",key,getTypeString(type),getResultString(result),matched_index);
result = Search(items,5,0,key=-1,type=GreaterThan,&matched_index);
printf(" %d %s %s %d\n\n",key,getTypeString(type),getResultString(result),matched_index);
}
static void test_ascending_using_assert()
{
int *items = (int *)malloc(sizeof(int) * 8);
int i = 0;
for (i = 0; i < 8; i++)
items[i] = i*2; // [0,2,4,6,8,10,12,14]
matched_index = -1;
assert(Search(items, 8, 1, -1, Equals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 19, Equals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 0 , Equals, &matched_index) == FoundExact);
assert(matched_index == 0);
matched_index = -1;
assert(Search(items, 8, 1, 13 , GreaterThan, &matched_index) == FoundGreater);
assert(matched_index == 7);
matched_index = -1;
assert(Search(items, 8, 1, 14 , GreaterThan, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 17 , GreaterThanEquals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 14 , GreaterThanEquals, &matched_index) == FoundExact);
assert(matched_index == 7);
matched_index = -1;
assert(Search(items, 8, 1, -1 , GreaterThanEquals, &matched_index) == FoundGreater);
assert(matched_index == 0);
matched_index = -1;
assert(Search(items, 8, 1, -2 , LessThan, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 0 , LessThan, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 1 , LessThan, &matched_index) == FoundLess);
assert(matched_index == 0);
matched_index = -1;
assert(Search(items, 8, 1, 16 , LessThan, &matched_index) == FoundLess);
assert(matched_index == 7);
matched_index = -1;
assert(Search(items, 8, 1, -3 , LessThanEquals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 8, 1, 14 , LessThanEquals, &matched_index) == FoundExact);
assert(matched_index == 7);
matched_index = -1;
assert(Search(items, 8, 1, 16 , LessThanEquals, &matched_index) == FoundLess);
assert(matched_index == 7);
free(items);
printf("All tests for Ascending array using Assert succeeded.\n");
}
static void test_descending_using_assert()
{
int *items = (int *)malloc(sizeof(int) * 20);
int j = 20;
for (int i = 0; i < 10; i++)
{
items[i] = j ; // [20,18,16,14,....,2]
j = j-2;
}
matched_index = -1;
assert(Search(items, 10, 0, -1, Equals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 10, 0, 19, Equals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 10, 0, 2 , Equals, &matched_index) == FoundExact);
assert(matched_index == 9 );
matched_index = -1;
assert(Search(items, 10, 0, 20 , GreaterThan, &matched_index) == NotFound);
assert(matched_index == -1 );
matched_index = -1;
assert(Search(items, 10, 0, 17 , GreaterThan, &matched_index) == FoundGreater);
assert(matched_index == 1 );
matched_index = -1;
assert(Search(items, 10, 0, 21 , GreaterThanEquals, &matched_index) == NotFound);
assert(matched_index == -1 );
matched_index = -1;
assert(Search(items, 10, 0, 20 , GreaterThanEquals, &matched_index) == FoundExact);
assert(matched_index == 0);
matched_index = -1;
assert(Search(items, 10, 0, 1 , GreaterThanEquals, &matched_index) == FoundGreater);
assert(matched_index == 9);
matched_index = -1;
assert(Search(items, 10, 0, 2, LessThan, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 10, 0, 3 , LessThan, &matched_index) == FoundLess);
assert(matched_index == 9);
matched_index = -1;
assert(Search(items, 10, 0, 1 , LessThanEquals, &matched_index) == NotFound);
assert(matched_index == -1);
matched_index = -1;
assert(Search(items, 10, 0, 4 , LessThanEquals, &matched_index) == FoundExact);
assert(matched_index == 8);
matched_index = -1;
assert(Search(items, 10, 0, 21 , LessThanEquals, &matched_index) == FoundLess);
assert(matched_index == 0);
free(items);
printf("All tests for Descending array using Assert succeeded.\n\n");
}
int main()
{
/* Assumptions
* ---------------------------------------------
* The Input array will be sorted
* Items will be non-NULL
* There are no duplicate items
* n_items will be > 0
* If key not found index = -1 will be returned
* ----------------------------------------------
*/
test_ascending();
test_descending();
test_ascending_using_assert();
test_descending_using_assert();
}