why is your array size k+1 instead of n+1?
try change cout << total << endl; to cout << total << â\nâ;
void solve() {
int n,q;cin>>n>>q;
string s;cin>>s;
int pre = 0;
for(int i = 0;i<n-1;i++){
if(s[i] == s[i+1])pre+=2;
else pre+=1;
}
while(q--){
int k;cin>>k;
k--;
if(s[k] == '0')s[k] = '1';
else s[k] = '0';
if(k == 0){
if(s[k] == s[k+1])pre++;
pre--;
}
else if(k == n-1){
if(s[k] == s[k-1])pre++;
pre--;
}
else{
if(s[k] == s[k+1] and s[k] == s[k-1])pre+=2;
if(s[k] != s[k+1] and s[k] != s[k-1])pre-=2;
}
cout << pre << endl;
}
}
can some help me out whatâs wrong with this code please?
No use 
bro
Is there any problem with code or approach!!!?
man, you messed up the if conditions. Also n == 1, only need to print 0 once. you printed multiple times
Accepted : CodeChef: Practical coding for everyone
I have ran Darshan Lokhandeâs exact code given in his video editorial⌠It gives wrong answerâŚ
@darshancool25 bhaiyaâŚPlease helpâŚ
My submission:
https://www.codechef.com/viewsolution/47293053
sorry, but i didnât understand where i messed up in my if condition. Can you tell me a test case where it fails, because I checked with many test cases and it works fine.
Maybe
have a look at some otherâs code i fixed
https://www.codechef.com/viewsolution/47293393
https://www.codechef.com/viewsolution/47292653
https://www.codechef.com/viewsolution/47290474
https://www.codechef.com/viewsolution/47291109
if(kk>=0 && kk<=n-1) { // you wrap the condition i == 0 and i == n - 1 inside this if, which will cause issue, better seperate into three conditions (i == 0, i == n - 1) and else 0 < i < n - 1, as you can see the fixed code
if(s[kk]==â0â)
s[kk] = â1â;
else
s[kk] = â0â;
if(kk==0){
if(s[kk]==s[kk+1]) dis+=1;
else dis-=1;
cout<<dis<<endl;
continue;
}
if(kk==n-1){
if(s[kk]==s[kk-1]) dis+=1;
else dis-=1;
cout<<dis<<endl;
continue;
}
if(s[kk]==s[kk-1]){
dis+=1;
}else{
dis-=1;
}
if(s[kk]==s[kk+1]){
dis+=1;
}else{
dis-=1;
}
cout<<dis<<"\n";
}
at least failed this edge case when string length is 1
1
1 3
0
1 1 1
should output:
0
you code
0
0
0
Hey, thanks for your help, there are some points, that I found right now:
I shifted all my code within while loop into a function and called this function into while loop and now it works.
2.So, the logic is correct and there must be no issue within any conditionals.
3. I think 0 0 0 is not an issue, because my accepted solution gives o/p 0 0 0 for this test case.
4.What can be the possible issue with thisâŚ
Well, I got the issue, In my solution, in the condition if(n==1) : I was using return, instead I had to use continue there.
Replacing that return with continue got it AC.
if(s[q]=='0') s[q]='1';
else s[q]='1';
you messed up here 
1 Like
Because you are skipping the input of all K queries for cases where N==1. Also take the initial input into a string, rather than character array. 
Can someone please find the error its giving rutime error .why?
@darshancool25
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
int main()
{
int t;
cin>>t;
while(tâ)
{
ll n,k;
cin>>n>>k;
string s ;
cin>>s;
if(n==1)
cout<<0<<endl;
if(n>1){
ll initial=0;
for(ll i=0;i<s.size()-1;i++)
{
if(s[i] == s[i+1])
initial+=2;
else
initial+=1;
}
//cout<<"Initial length of the string is "<<initial<<endl;
ll i=0;
int p;
while(i<k)
{
//int p;
cin>>p;
int a=p-1;
if(s[p-1] == '0')
//s[p-1]='1';
//int a = p-1;
s.replace(a,1,"1");
else
//s[p-1]='0';
s.replace(a,1,"0");
//cout<<"Now the string is "<<s<<endl;
if(p==n)
{
if(s[p-1] == s[p-2])
{
initial+=1;
}
else
initial-=1;
}
else if(p==1)
{
if(s[p-1] == s[p])
{
initial+=1;
}
else
initial-=1;
}
else
{
if(s[p-1] == s[p-2] && s[p-1]==s[p])
initial+=2;
else if((s[p-1]==s[p-2] && s[p-1]!=s[p]) || (s[p-1]!=s[p-2] && s[p-1]==s[p]))
{
continue;
}
else
{
initial-=2;
}
}
cout<<initial<<endl;
i++;
}
}
}
return 0;
}
Thanks a lot for pointing out my mistake.
#include
using namespace std;
int main() {
// your code goes here
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t;
cin>>t;
while(tâ){
long long int n,k;
cin>>n>>k;
if(n==1){
cout<<â0â<<"\n";
continue;
}
string s;
cin>>s;
long long int sum=0;
for(long long int i=0;i<=n-2;i++){
if(s[i]!=s[i+1])
sum=sum+1;
else
sum=sum+2;
}
for(long long int i=0;i<k;i++){
long long int a;
cin>>a;
if(a==1){
if(s[0]==s[1])
sum=sum-1;
else
sum=sum+1;
}
else if(a==n){
if(s[n-2]==s[n-1])
sum=sum-1;
else
sum=sum+1;
}
else{
if(s[a-1]==s[a-2])
sum=sum-1;
else
sum=sum+1;
if(s[a-1]==s[a])
sum=sum-1;
else
sum=sum+1;
}
if(s[a-1]=='0')
s[a-1]='1';
else
s[a-1]='0';
cout<<sum<<"\n";
}
}
return 0;
}
Can somebody tell me what is wrong with this code on submission?
`#include<bits/stdc++.h>
using namespace std;
#define loop(i,n) for(int i=0;i<n;i++)
#define ll long long
#define scan(arr) for(auto &it:arr)cin>>it;
#define print(a) {for(auto it:a)cout<<it<<" ";cout<<endl;}
int main() {
int t;
cin>>t;
while(tâ)
{
int n,k;
cin>>n>>k;
string s;
cin>>s;
int dist=0;
// cout<<s<<endl;
for(int i=1;i<n;i++)
{
if(s[i]!=s[i-1])
dist++;
else
dist+=2;
}
// cout<<s<<endl;
for(int i=1;i<=k;i++)
{
int q;
cin>>q;
if(q==1&&s[q]==s[q-1])
{
distâ;
}
else if(q==1&&s[q]!=s[q-1])
{
dist++;
}
else if(q==n&&s[q-1]!=s[q-2])
{
dist++;
}
else if(q==n&&s[q-1]==s[q-2])
{
distâ;
}
else if(s[q-1]!=s[q]&&s[q-1]!=s[q-2])
{
dist+=2;
}
else if(s[q-1]==s[q]&&s[q-1]==s[q-2])
{
dist-=2;
}
if(s[q-1]=='1')
s[q-1]='0';
else
s[q-1]='1';
// cout<<s<<endl;
cout<<dist<<endl;
}
}
return 0;
}`
Can someone help me out with this code??
Itâs passing many test cases but I cant figure out where it fails.
https://www.codechef.com/viewsolution/47308647
GUYS please help me find out mistake ,i have tried a lot but still not getting whats wrong .
I have checked almost all cases including n=1 and getting correct answer , but still WA .Please help me out
My code always getting runtime error :
#include <bits/stdc++.h>
#define ll long long int
using namespace std;
int main()
{
int t;
cin>>t;
while(t--)
{
int n,k;
cin>>n>>k;
string s;
cin>>s;
int d = 0;
for(int z=0;z<=s.size()-2;z++)
{
if(s[z]==s[z+1])
d+=2;
else
d+=1;
}
int len = 0;
while(k--)
{
int j;
cin>>j;
j--;
if(s[j] =='1')
s[j] = '0';
else
s[j] = '1';
if(j>0) //left
{
if(s[j-1]==s[j])
len++;
else
len--;
}
if(j<s.size()-1) //right
{
if(s[j+1]==s[j])
len++;
else
len--;
}
d = d + len;
cout<< d <<"\n";
len = 0;
}
}
return 0;
}