Giving Wrong output

Question

I was trying Leetcode problem https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram/

It is to return minimum number of letters that needs to be changed to make the two strings anagrams. However when pass a string "leetcode" and other string "practise" , it should give output as 5 but giving 3.

LOGIC:

Start a for loop taking letters of first string one by one. Say take 'L'
Then count how many letters i.e 'L' are there in the first string. Store its value in val i.e. val = 1;
Then similarly count the number of 'L' in second string and store the value in count i.e. count=0;
Then if val>count , subtract val - count i.e. 1-0 = 1 and store it in sum;
Now similarly do all the above 4 steps in every letter of the 1st string and add every result in fsum i.e. fsum+=sum;
Thus fsum will tell the number of letters needed to be changed.

Could anybody help me in finding my mistake ?

class Solution {
public:
    int minSteps(string s, string t) {
        vector<char> v1;
        char c;
        int flag;
        int val=0;
        int count=0;
        int len=0;
        int sum=0;
        int d=0;
        int fsum=0;

        for(int i=0;i<s.length();i++){
            c=s[i];
            flag=0;

            vector<char> :: iterator it = find(v1.begin(),v1.end(),c);

            if(it != v1.end()){ 
                flag=1;
                break;
            }
            else 
            if(flag==0){
                v1.push_back(c);

                len=s.length();
                d=0;
                val=0;
                while(len){
                    if(c==s[d]) val++;
                    d++; len--;
                } 

                //comparison in 2nd string
                len=t.length();
                d=0;
                while(len){
                    if(c==t[d]) count++;
                    d++; len--;
                }

                if(val>count){ 
                    sum=val-count;
                    fsum+=sum;
                    val=count=0;
                }
            }
        }
        return fsum;
    }
};

Side remark, please initialize your ints like flag, val, count. And put them on separate declarations. — Benjam, May 22 '20 at 07:02
maybe it won't help with this error but it will help to prevent many others — 463035818_is_not_an_ai, May 22 '20 at 07:07
sorry, but you didn't get the point. You should initialize your variables. You never initialize `count` and using its value causes undefined behavior — 463035818_is_not_an_ai, May 22 '20 at 07:25
It would help if you'd first explain the logic you're trying to implement, and then add the code after that. — ghost, May 22 '20 at 07:42
@KaranNayyar FYI -- This is actually a 3 or 4 line solution. Two calls to `std::sort`, and a call to `std::set_difference` on the sorted ranges. That's it. [See this](http://coliru.stacked-crooked.com/a/f1b03dad47d48bf0) — PaulMcKenzie, May 22 '20 at 08:34
@PaulMcKenzie I checked ur code and it is good but I need to figure out what is wrong in my approach. — Karan Nayyar, May 22 '20 at 09:49

score 0 · Accepted Answer · answered May 22 '20 at 08:04

0

Your logic seems to be 'about' right. However, check the following piece of your code:

vector<char> :: iterator it = find(v1.begin(),v1.end(),c);
if(it != v1.end()){ 
        flag=1;
        break;
}

What this says is, if character c has already been seen before, BREAK out of the loop. I assume what you meant was CONTINUE with the next iteration of the loop.

This is because when you break, you do not break the loop over the vector v1 (I think that's what you assumed). Rather you break the loop over the string s.

answered May 22 '20 at 08:04

ghost

1,107
3
12
31

There are also some other missing pieces, but as I said, we'll figure that out together :) – ghost May 22 '20 at 08:07
I did with continue; statement also but same result – Karan Nayyar May 22 '20 at 08:15
Never write statements like val=count=0. Change it to val=0; count = 0; The reason is, every statement has a return value and something it does. When you say val=count=0, it's interpreted as val = (count = 0), so count = 0 is an expression, and it's return value is assigned to val. – ghost May 22 '20 at 08:59
@KaranNayyar did you figure out the flaw yet? – ghost May 22 '20 at 09:25
nope , I didn't find it yet and I also have done the changes in all and count – Karan Nayyar May 22 '20 at 09:48
So, the issue is, you're only setting count to 0 when val>count. Suppose there's a case when val – ghost May 22 '20 at 10:24
Thank You very much , It worked finally and it was great that u looked into :) – Karan Nayyar May 22 '20 at 10:44

Giving Wrong output

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