Questions tagged [binary-search]

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Purpose of sizeof(book)/sizeof(string) in lectures' binary sort?

string book[] = { "Chen", "Kernighan", "Leitner", "Lewis", "Malan", "Muller", "Seltzer", "Shieber", "Smith" } int main(...
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23 views

Code won't progress unless user inputs a number

I was writing a binary search function before finishing lecture 3 because I wanted to do some practice on my own. I was using scanf, which I had looked up, as I wanted to learn how to code without the ...
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1answer
31 views

find problem with my code - CPU overload

I cannot figure out what is wrong with my code. /** * Returns true if value is in array of n values, else false. */ bool search(int value, int values[], int n) { // ensures that the n is non ...
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1answer
65 views

pset3 find less comfortable if else expression result unused

I do not understand why I get an errors: error: expected ';' after expression else (value > values[l]) and helpers.c:40:21: error: expression result unused [-Werror,-Wunused-value] ...
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1answer
40 views

CS 50 - pset3 find helpers: Why do binary search and selection short not work?

the command line yells at me but I cannot find out why. Any ideas what could be wrong? Here is my code: /** * helpers.c * * Helper functions for Problem Set 3. */ include include "helpers.h" /...
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2answers
236 views

PSET3 find having trouble. Can someone help?

For some reason bubble sort is not working. Can someone help. binary search bool search (int target, int array[],int length) { int end = length-1; int start = 0; while (array[start] < ...
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1answer
69 views

pset3: sort and search work in separate files, but my helpers.c doesn't work

I dealt with sorting in a separate file first, and then I dealt with searching in another file. They seem to work okay or at least worked for the numbers I feed in, but when I put them in helpers and ...
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26 views

For pset3 binary search will this code work?

Here is the code . bool binary_search (int target, int array[],int length) { int end = length-1; int start = 0; while ( array[end_num]- array[start_num] > 0) { ...
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1answer
34 views

do I need recurson for binary search?

Also do I need recursion for any of the pset3 solutions? If yes any good sources on recursion. There was a quick example in lecture 3. Will that suffice? Preferably a video. I realize I could just ...
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1answer
59 views

Find.c - Binary Search probable integer overflow

Here's the gist: https://gist.github.com/Securiteru/a83e4f1a028acd0b1013def793b5dcdc And the output: ... 60697 61151 61190 61275 61460 61608 61618 61746 61750 61822 62111 62178 62183 62311 62448 ...
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1answer
416 views

Pset3, Find, search

In "Find" problem, something seems wrong with my binary search Algorithm, because in check50, helpers.c wouldn't compile, I tried to compile it, then it gave me this weird error: clang -fsanitize=...
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2answers
62 views

pset 3 binary search help

I am working on pset 3 for cs50 on edx, and I'm having quite a bit of trouble with the binary search problem. My program worked fine when I tested it with a linear search (so I think the problem isn'...
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1answer
104 views

PSET3 Binary Search Function Infinite Loop

When I try running find.c inputting: ./generate 1000 50 | ./find 127 it should return that the value (127) was found, however when I do it with my code, it seems to create an infinite loop. Also, ...
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2answers
174 views

Pset3 helpers.c

i'm stuck in binary search. Check50 doesn't pass all the checks and it doesn't find the needle, I feel like the algorithm i have implemented is correct but it doesn't work. I've been stuck in this for ...
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2answers
95 views

Binary Search for helpers.c

so as the title suggests I am having some trouble with my implementation of binary search. So based on the logic shown in the lecture, I think my implementation is fine, indeed it works for the cases ...
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2answers
103 views

Binary Search Pset 3 help

As my question is titled, I would appreciate help with my binary search, shown below. Currently, the search will always return false. I am almost certain that my sorting algorithm is correct, as it ...
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2answers
157 views

Segmentation Fault pset3 for Find

I'm getting a segmentation fault error and I can't figure out why. void sort(int values[], int n) { // TODO: implement a sorting algorithm for (int i = 0; i<n; i++) { if ((n!=i+...
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0answers
49 views

Result doesn't match expected output

I just finished the helpers.c pset, where you have to implement a counting sort and then a binary search. I havent made it recursive yet but it works in all of my own test cases. I also ran the ./...
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1answer
72 views

pset3: search (am I in the right track??)

bool search(int value, int values[], int n) //search for middle lists if (value == values [n / 2]) { return 1; } //number greater search left else if ( value > values[n / 2 ]) { search(int ...
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1answer
94 views

Pset 3 Recursive Binary Search problems - Always returns true

I have tried almost everything and edited my code a hundred times in search of an answer. It seems that whenever I run the program (find.c) the result always resolves to true. Not sure where the ...
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1answer
12k views

Question about binary search. Please help!

https://www.youtube.com/watch?v=5xlIPT1FRcA&t=200s I am struggling to understand how to implement binary search. According to the video, there are 14 numbers in the array. Then he goes on to ...
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1answer
665 views

cs50x pset3 find - Need help with the counting sort

can someone please look at my code and tell me where I went wrong with my counting sort algorithm (Or binary search algorithm, if that's where the problem lies...?). Please and thank you. Binary ...
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2answers
29 views

C: Binary Search searches and finds but incorrect exit code

This code is finding all the numbers correctly. Only problem is it's throwing error of "\ expected an exit code of 1, not 0" when the number is not present. Help would be appreciated. bool search(int ...
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1answer
28 views

Advice re: Binary search - various issues

I need advice as to what to change in this code to make it work. I am new at this so I need specifics, please. Please, no opinions on whether it's trash or what mark you would give if grading it. That ...
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2answers
36 views

C: Pset 3: Binary Search - 'expected an exit code of 0, not 1' (not finding n)

This is an attempt at binary search. n is the user input (from main script). This code compiles but doesn't find the needle in the haystack. I'm a bit lost and would welcome assistance. bool ...
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1answer
47 views

please help me with this binary search

for some reason this binary search code keeps returning true, when providing the haystack from generate.c, even if the "needle" isnt there. when manually inputing the haystack, the code runs perfectly....
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1answer
94 views

Pset 3: Find (more comfortable) - child exited with status 255 & exits with wrong code

I ambitiously decided to try the more comfortable version of this task, although I'm very much "less comfortable" with regard to any computer skills... Before I give up, I'd like to ask you what's ...
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214 views

PSET3 \ expected an exit code of 0, not 1 (find.c)

I successfully built my program and went on to check it using check50 only to discover this :) helpers.c exists :) helpers.c compiles :) finds 42 in {42,43,44} :) finds 42 in {41,42,43} :) finds 42 ...
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1answer
93 views

Pset3 Find - Not sure what is wrong with helpers.c code

I am not sure what is wrong with the code. It seems to work on some of the criteria when using cs50's check50, but does not work on others. There also does not seem to have a pattern about the wrong ...
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1answer
35 views

Recursive function problem - return value

I am getting the following error below. It has to do with my binarySearch function. helpers.c:149:1: error: control may reach end of non-void function [-Werror,-Wreturn-type] } ^ However I have a ...
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1answer
47 views

Pset3 helpers.c while loop exiting unexpectedly

I am trying to implement a binary search algorithm. However, my while loop isn't working as expected. Having used printf and debug50 with a list of 100 numbers, it seems that the while loop only gets ...
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1answer
96 views

Binary Search pset3

bool search(int value, int values[], int n) { int found = 0; int notfound = 0; int minindex = 0; int maxindex = n; int midindex = 0; do { midindex = (minindex + maxindex) / 2; if (minindex &...
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1answer
331 views

PSet 3, binary search implementation

I'm struggling with implementation of binary search in PSet 3, and my code can't quite get past check50. Here's my code: bool search(int value, int values[], int n) { // TODO: implement a ...
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1answer
160 views

helpers.c passes check50 but fails ./generate 1000 50 | ./find 128

check50 gives me all smiles, but when I run the test code ./generate 1000 50 | ./find 127 or 128 they both return "Found needle in haystack". How is that possible? And also, can I be sure my code is ...
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1answer
39 views

pset3 binary search , shows errors in check50

i don't understand acc. to the algorithm it should work correctly , but it doesn't
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1answer
94 views

pset3 binary search , problems with check50

i have tried a lot but cannot find the meaning of the last two errors of check50 please help
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1answer
26 views

pset3: When testing binary search code, how do I print when needle is found?

I would like to test if my binary search function is working correctly. I have created an array that is passed into a working bubble sort function. Printing the sorted array works just fine, all I ...
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1answer
75 views

Pset3 recursive binary search function - check50 gives me four :( and I don't know why

I would be really grateful if someone could offer me a hint as to where I'm going wrong with this - I've been stuck for a couple of days now. When I work through the code step by step on paper it ...
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1answer
51 views

binary search algorithm

Many sources say that you need to put "int l = n" the element next to last instead of "int l = n - 1"(int f = 0; int l = n - 1; int mid;) in my example. I am not sure why? Moreover it seems my code ...
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1answer
44 views

return -1 does not end function execution

This is my code. 65 int BinarySearch(int key, int array[], int min, int max) 66 { 67 int mid; 68 69 if (max < min) 70 { 71 return -1; 72 } 73 else 74 ...
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1answer
71 views

How do I set a pointer to access the left half of an array? [PSET 3 - Binary search]

I'm having trouble accessing only the left half of an array, doing the same for the right half works fine for now, at least I'm not getting any errors. I figured accessing the array using pointers ...
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1answer
177 views

Segmentation fault in find.c

I've been working on find.c for a long time now and I've managed to get to the point where it will return the correct output when the needle is in the haystack, but when it isn't I get a segmentation ...
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2answers
67 views

find.c compiles but fails check50 - I believe binary search is to blame

Why does my code fail check50? This is the code of my binary search. I know it's buggy, and I spent the last hours reading answers to similar questions, the information I found doesn't quite cut it ...
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1answer
98 views

Check50 is claiming that it's recieving an exit code of 0 rather than 1 (different scenario)

I know this question has been answered before (pset 3 "search": expected an exit code of 0, not 1), but I took a look at it, and it seems that the scenario in which the person asked the ...
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1answer
224 views

Stuck in loop on Binary Search

I have some problems with my Binary search and would greatly apprecaite help in this. I've debugged it and it seems that my "mid" variable doesn't change. As such, if "value" doesn't equal value[mid] ...
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2answers
54 views

binary search pset 3 pointer to integer error

I am trying my hands on binary search. I get those pointer to integer errors :( Can sonmeone more experience give me a hand ? bool search(int value, int values[], int n) { int first=0; int last=n-1; ...
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1answer
23 views

Binary search: always false when 2 or 3 numbers entered

My binary search works correctly when you enter 1,4,5,6,7 (etc)... numbers or 'haystacks'. However, when 2 or 3 numbers or 'haystacks' are entered, false is always returned. I have tried everything I ...
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1answer
65 views

What's wrong with my recursive binary search function? [duplicate]

I've spent hours on this, have tried multiple configurations based on code I can find online, but am getting no where. Any input would be appreciated. I'm trying to make a recursive, binary search ...
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1answer
166 views

Pset 3 - Binary Search - clang: error: linker command failed with exit code 1

When I compile, with "make find", the following code: I get: So, if I'm interpreting this correctly, there's an undefined reference to search on line 58 of find.c, which is -- if (search(needle, ...
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1answer
42 views

why doesn't my implementation to binary search correctly handle not finding an element?

I was practicing to write the code for binary search after watching its short, before starting on pset3. The code that I wrote asks for the length of array, then sorts it and asks for the number to ...