In this question we have to maximize the modulo function. A string is given And we have remove the element and check after removing a element which number give the maximum modulo answer.
Link:- https://www.hackerearth.com/practice/data-structures/arrays/1-d/practice-problems/algorithm/maximize-modulo-2-0cb15ded/
My code is not able to pass all test case it shows runtime error or wrong answer in most test case.
#include "bits/stdc++.h"
using namespace std;
int countDigit(long long n)
{
int count = 0;
while (n != 0)
{
n = n / 10;
++count;
}
return count;
}
int main() {
int t;
cin>>t;
for(int i=0;i<t;i++){
int m,k;
cin>>m>>k;
string s;
cin>>s;
int ans = INT_MIN;
int n = countDigit(k);
if(n == m && stoi(s) < k){
cout<<stoi(s)<<endl;
continue;
}
else{
for(int i=0;i<m;i++){
string a = "";
for(int j=0;j<m;j++){
if(j == i){
continue;
}
else{
a += s[j];
}
}
int mo;
int num = stoi(a);
mo = num%k;
if(mo > ans){
ans = mo;
}
}
cout<<ans<<endl;
}
}
return 0;
}
Please tell me where i'm making the mistake or please tell me any better way to solve this question?
Related
I found this code online on tutorials point. link https://www.tutorialspoint.com/cplusplus-program-to-generate-all-possible-combinations-out-of-a-b-c-d-e.
I tried to think of how to modify it so that it would randomly a single combination from the generated list, but I'm haven't figured it out yet.
#include<iostream>
using namespace std;
void Combi(char a[], int reqLen, int s, int currLen, bool check[], int l)
{
if(currLen > reqLen)
return;
else if (currLen == reqLen) {
cout<<"\t";
for (int i = 0; i < l; i++) {
if (check[i] == true) {
cout<<a[i]<<" ";
}
}
cout<<"\n";
return;
}
if (s == l) {
return;
}
check[s] = true;
Combi(a, reqLen, s + 1, currLen + 1, check, l);
check[s] = false;
Combi(a, reqLen, s + 1, currLen, check, l);
}
int main() {
int i,n;
bool check[n];
cout<<"Enter the number of element array have: ";
cin>>n;
char a[n];
cout<<"\n";
for(i = 0; i < n; i++) {
cout<<"Enter "<<i+1<<" element: ";
cin>>a[i];
check[i] = false;
}
for(i = 1; i <= n; i++) {
cout<<"\nThe all possible combination of length "<<i<<" for the given array set:\n";
Combi(a, i, 0, 0, check, n);
}
return 0;
}
im not a c++ specialist, but i think you should add a random number from -ArrayLenght to ArrayLenght, at least this works in python(which is written in c++)
i hope i understood your question right
Please help me to solve the query that this code runs infinitely at a particular line.
It does not give any output as at the end of the code I write the code to print the vector. Even after I assign any value to vector "result" manually still it is not giving any output. why is it so?
#include<bits/stdc++.h>
using namespace std;
bool authorize(int strValue, int value, int M)
{
long int newValue = (strValue - (value * 131) % M);
if (newValue >= 48 && newValue <= 57)
return true;
if (newValue > 65 && newValue <= 90)
return true;
if (newValue >= 97 && newValue <= 122)
return true;
return false;
}
int hashingfunct(string str, int M)
{
long int P, F, sum = 0;
int len = str.length();
for (int i = 0; i < len; i++)
{
P = pow(131, len - i - 1);
F = (int)str[i];
sum += (F * P) % M;
}
sum = sum % M;
return sum;
}
int main()
{
int n = 5;
string str1, str2;
vector<vector<string> > events;
for (int i = 0; i < n; i++) {
cin >> str1 >> str2;
vector<string > temp;
temp.push_back(str1);
temp.push_back(str2);
events.push_back(temp);
}
for (int i = 0; i < n; i++) {
cout << events[i][0] << events[i][1];
}
/*
INPUT FORMAT:
setpassword 1
setpassword 2
setpassword 3
authorize 49
authorize 50
*/
vector<int> result;
int j = 0;
long int m = pow(10, 9);
long int M = m + 7;
long int value, strValue;
for (int i = 0; i < events.size(); i++)
{
strValue = stoi(events[i][1]);
if (events[i][0] == "setPassword") {
value = hashingfunct(events[i][1], M);
}
else if (strValue == value)
result[j++] = 1;
else if (authorize(strValue, value, M))
result[j++] = 1;
else
result[j++] = 0;
}
for (int i = 0; i < result.size(); i++) {
cout << result[i];
}
}
Your program has complete Undefined Behaviour.
Let's get started with the first problem. In the following check code
long int value, strValue; // not initialised
for (int i = 0; i < events.size(); i++)
{
// ...
// here it should have been "setpassword" (i.e. all are small letters)
if (events[i][0] == "setPassword")
{
// if the check fails the `value` never get initialised!
value = hashingfunct(events[i][1], M);
}
// If the `value` not been initialised, check happens with any garbage value here!
else if (strValue == value)
// ...other code
}
You are checking whether the string is "setPassword" instead of "setpassword" (i.e. see in the events vector, all the strings are small letters).
If that goes wrong, the value will never get initialized, meaning it holds any garbage value and hence conducting this check else if (strValue == value) can cause any behaviour to your program (aka Undefined Behaviour).
Secondly, the vector<int> result; is empty at the beginning. Therefore accessing elements via std::vector::operator[] later
result[j++] = 1;
// ...
result[j++] = 1;
// ...
result[j++] = 0;
triggers the access out of bounds (UB). There you need just result.emplace_back(/*value*/); or result.push_back(/*value*/);, and no need of redutant variable j.
In short, you need
#include <iostream>
#include <vector>
#include <string>
// ..other functions
int main()
{
std::vector<std::vector<std::string> > events {
{"setpassword", "1"}, // can be also user input, like in your example
{"setpassword", "2"},
{"setpassword", "3"},
{"authorize", "49" },
{"authorize", "50" }
};
std::vector<int> result;
const long int M = pow(10, 9) + 7;
long int value{ 0 }, strValue{ 0 }; // default initialization
for (const std::vector<std::string> row: events) // better use range-based loop
{
strValue = std::stoi(row[1]);
if (row[0] == "setpassword") {
value = hashingfunct(row[1], M);
if (strValue == value)
result.emplace_back(1);
else if (authorize(strValue, value, M))
result.emplace_back(1);
}
else
result.emplace_back(0);
}
}
As a side note,
Please do not use using namespacestd;
Why should I not #include <bits/stdc++.h>?
Corrected code
#include<bits/stdc++.h>
using namespace std;
bool authorize(long int strValue,long int value,int M){
long int value1=value*131;
long int newValue=(strValue-(value1%M))%M;
if(newValue>=48 && newValue<=57)
return true;
if(newValue>=65 && newValue<=90)
return true;
if(newValue>=97 && newValue<=122)
return true;
return false;
}
int hashingfunct(string str,int M){
long int P,F,sum=0;
int len=str.length();
for(int i=0;i<len;i++){
P=pow(131,len-i-1);
F=(int)str[i];
sum+=(F*P)%M;
}
sum=sum%M;
return sum;
}
int main(){
int n=5;
string str1,str2;
vector<vector<string> > events;
for (int i=0;i<n;i++){
cin>>str1>>str2;
vector<string > temp;
temp.push_back(str1);
temp.push_back(str2);
events.push_back(temp);
}
/*
setPassword cAr1
authorize 223691457
authorize 303580761
setPassword d
authorize 100
*/
vector<int> result;
int j=0;
long int m=pow(10,9);
long int M=m+7;
long int value,strValue;
for(int i=0;i<events.size();i++){
if(events[i][0]=="setPassword"){
value=hashingfunct(events[i][1],M);
continue;
}
strValue=stoi(events[i][1]);
if(strValue==value)
result.push_back(1);
else if(authorize(strValue,value,M))
result.push_back(1);
else
result.push_back(0);
}
for(int i=0;i<result.size();i++){
cout<<result[i];
}
}
It is good array only if gcd(val[i],val[j])>1
Here,
gcd(a,b) = Greatest common divisor of two numbers.
Split the array has one parameter
Val: A integer array of n integer
Here are two examples.
Sample Input 0:
5 // no of value in an integer
2
3
2
3
3
Sample Output 0:
2
Sample Input 1:
5 //no of value in an integer
3
5
7
11
2
Sample Output 1:
5
example of sample input 0
subarray[1..3] ={2,3,2} here gcd(2,2)>1
subarray[4..5]={3,3} gcd(3,3)>1
#include <bits/stdc++.h>
using namespace std;
string ltrim(const string &);
string rtrim(const string &);
Now how to impelement the splitTheArray() function?
You need to find the minimum number of subarrays such that in each sub-array, first and last elements' gcd > 1. You can do it easily by O(Nˆ2) complexity.
int splitTheArray(vector<int> val) {
// implement this function
int sz = val.size();
if(sz == 0) return 0;
int ind = sz - 1;
int subarray = 0;
while(ind >= 0) {
for(int i = 0; i <= ind; i++) {
if(__gcd(val[ind], val[i]) > 1) {
subarray++;
ind = i-1;
break;
}
}
}
return subarray;
}
#include <iostream>
#include <vector>
#include <fstream>
#include <string>
using namespace std;
int gcd(int a, int b)
{
if (b == 0)
return a;
return gcd(b, a % b);
}
int max(int a, int b)
{
return (a > b) ? a : b;
}
int min(int a, int b)
{
return (a < b) ? a : b;
}
int solve(vector<int> vec)
{
int n = gcd(vec[0], vec[vec.size() - 1]);
if (n > 1)
return 0;
int con = 0 , flag = 0 , j=0 , i=0 , flag2=0;
for (i = j; i < vec.size()/2; i++)
{
i = j;
if (i >= vec.size())
break;
int f = vec[i];
flag = 0;
for (j = i+1; j < vec.size(); j++)
{
int l = vec[j];
int ma = max(f, l);
int mi = min(f, l);
n = gcd(ma, mi);
if (flag)
{
if (n > 1)
con++;
else
break;
}
if (n > 1)
{
flag = 1;
flag2 = 1;
con++;
}
}
}
if (!flag2)
return vec.size();
return con;
}
int main()
{
int n;
cin >> n;
vector<int> vec;
for (int i = 0; i < n; i++)
{
int tm;
cin >> tm;
vec.emplace_back(tm);
}
cout<<solve(vec);
return 0;
}
#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define boost ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
void solve()
{
int n,i,j;
cin>>n;
int A[n+1],DP[n+1];
for(i=1;i<=n;i++)
cin>>A[i];
memset(DP,0,sizeof(DP));
unordered_map<int,int> M;
for(i=1;i<=n;i++)
{
vector<int> Fact;
Fact.push_back(A[i]);
for(j=2;j*j<=A[i];j++)
{
if(A[i]%j==0)
{
if(j*j==A[i])
{
Fact.push_back(j);
}
else
{
Fact.push_back(j);
Fact.push_back(A[i]/j);
}
}
}
int ans=DP[i-1]+1;
for(j=0;j<Fact.size();j++)
{
if(M.find(Fact[j])==M.end())
{
M[Fact[j]]=DP[i-1];
}
else
{
ans=min(ans,M[Fact[j]]+1);
}
}
DP[i]=ans;
}
cout<<DP[n]<<endl;
}
int32_t main()
{
boost;
int t=1;
// cin>>t;
for(int i=1;i<=t;i++)
{
//cout<<"Case #"<<i<<": ";
solve();
}
}
Time Complexity: N*Sqrt(max(A[i]))
P.S There can be a optimization of calculation of factor using the sieve instead of calculating factor every time for every number.
#include <bits/stdc++.h>
using namespace std;
int main()
{
int n;
cin>>n;
vector<int>a(n);
for(int i=0;i<n;i++){
cin>>a[i];
}
vector<int>dp(n+1,0);
dp[n-1]=1;
for(int i=n-2;i>=0;i--){
dp[i]=1+dp[i+1];
for(int j=i+1;j<n;j++){
if(__gcd(a[i],a[j])>1)
dp[i]=min(dp[i],1+dp[j+1]);
}
}
cout<<dp[0];
return 0;
}
i am a beginner to c++ but i wouldn't have asked this question if i didnt spend hours on it.
The code is about finding primes between two numbers in the most efficient way where maximum limit is 10^9.
The following code gives me runtime error but i have no idea why.. help
#include <iostream>
#include <stdio.h>
#include <math.h>
using namespace std;
long int prime[32000];
bool isprime(long int a){
for(long int i = 3; i <= 32000; i+=2){
if(a%i == 0){
return false;
}
}
return true;
}
void generateprimes(){
long int a = 0;
for(long int i = 3; i < 31623 ; i+=2){
if(isprime(i)){
prime[a] = i;
a++;
}
}
}
bool newisprime(long int a){
long int x =0;
for(long int i = prime[x]; i <= sqrt(a); i = prime[++x]){
if(a%i == 0){
return false;
}
}
return true;
}
void generateprimes_inbetween(long int n,long int m){
if(n%2 == 0){
++n;
}
if(n == 1){
printf("2\n");
n = 3;
}
for(long int i = n; i <= m ; i+=2){
if(newisprime(i)){
printf("%d\n",i);
}
}
}
int main() {
long int a,b,c;
scanf("%ld",&a);
generateprimes();
for(long int i = 0; i < a ; i++){
scanf("%ld %ld",&b,&c);
generateprimes_inbetween(b,c);
printf("\n");
}
return 0;
}
In isprime() you loop through ALL numbers in your array prime[]. But at startup, as it's global data, most of them will be 0, so that a%i will result in a fatal divide by 0.
You have somewhere to keep track of the numer of primes that you've stored in your array and only test against the primes that you've stored there.
Supposing that it's homework and you're not allowed to use vectors, you could do it as follows:
const size_t max_primes = 32000; // avoid hard coded values
unsigned long prime[max_primes] {2, 3}; // prefilled values
size_t nprimes = 2; // number of primes in the array
bool isprime(unsigned long a){
for(size_t i = 0; i < nprimes; i++){
if(a%prime[i] == 0)
return false;
}
return true;
}
void generateprimes(){
nprimes = 2;
for(unsigned long i = 3; nprimes<max_primes && i < ULONG_MAX; i += 2){
if(isprime(i)){
prime[nprimes] = i;
nprimes++;
}
}
}
bool newisprime(unsigned long a){
size_t x = 0;
for(unsigned long i = prime[x]; i <= sqrt(a) && x<nprimes; i = prime[++x]){
if(a%i == 0)
return false;
}
if(x == nprimes) {
cout << "Attention: Reaching end of prime table !!" << endl;
}
return true;
}
Some remarks:
for the index, it's safer to use the unsigned type size_t.
make sure that whenever you use an index, it remains within the bounds
as you work with positive numbers, it could make sense to use unsigned long
I want to find the minimum difference among all elements of an array. I read through various other questions, but couldn't find the exact source of the error in the following code.
#include<iostream>
#include<stdio.h>
#include<cstdlib>
using namespace std;
void quicksort(long int *lp, long int *rp);
int main()
{
int t,n;
long int s[5000];
cin>>t;
while(t--){
cin>>n;
for(int i=0;i<n;i++) cin>>s[i];
quicksort(&s[0],&s[n-1]);
//cout<<"passes:"<<passes<<endl;
//for(int i=0;i<n;i++) cout<<s[i]<<" ";
long int min = abs(s[1]-s[0]);
//cout<<endl<<min;
for(int i=1;i<(n-1);i++){
long int temp = abs(s[i]-s[i+1]);
if (temp <= min) min = temp;
}
cout<<min;
}
}
void quicksort(long int *lp,long int *rp){
int arraysize= (rp-lp)+1;
if(arraysize > 1){
long int *pivot = (lp+(arraysize/2));
long int swap=0;
long int *orgl = lp;
long int *orgr = rp;
while(lp!=rp){
while (*lp < *pivot) lp++;
while (*rp > *pivot) rp--;
if (lp == pivot) pivot=rp;
else if (rp == pivot) pivot=lp;
swap = *lp;
*lp = *rp;
*rp = swap;
if((*lp == *pivot) || ( *rp == *pivot)) break;
}
quicksort(orgl,pivot-1);
quicksort(pivot+1,orgr);
}
}
The problem statement is given in this link : http://www.codechef.com/problems/HORSES
Can you please identify the error in my program ?
You are using C++ so instead of using your custom quicksort which is not really guarantee O(n*logn) you better use sort from <algorithm>.
This logic looks good:
long int min = abs(s[1]-s[0]);
//cout<<endl<<min;
for(int i=1;i<(n-1);i++){
long int temp = abs(s[i]-s[i+1]);
if (temp <= min) min = temp;
}
By the way:
cout<<min;
Add cout<<min << endl;
The line
if((*lp == *pivot) || ( *rp == *pivot)) break;
is wrong. Consider
5 4 7 5 2 5
^
pivot
Oops.
This line
long int temp = abs(s[i]-s[i+1]);
is unnecessarily complex. Since the array is (supposedly) sorted,
long int temp = s[i+1] - s[i];
does the same without calling abs.
sort(s, s + n); // #include <algorithm> O(n*log n)
Otherwise sort/find minimum algorithm is correct. There are O(n) algorithms based on randomization, bucket sort.
#include <algorithm> // sort()
#include <iostream>
int main() {
using namespace std;
int ntests, n;
const int maxn = 5000; // http://www.codechef.com/problems/HORSES
int s[maxn];
cin >> ntests; // read number of tests
while (ntests--) {
cin >> n; // read number of integers
for (int i = 0; i < n; ++i) cin >> s[i]; // read input array
sort(s, s + n); // sort O(n*log n)
// find minimal difference O(n)
int mindiff = s[1] - s[0]; // minn = 2
for (int i = 2; i < n; ++i) {
int diff = s[i] - s[i-1];
if (diff < mindiff) mindiff = diff;
}
cout << mindiff << endl;
}
}
#include <iostream> using namespace std;
int main() {
int a[] = {1,5,2,3,6,9};
int c=0;
int n = sizeof(a)/sizeof(a[0]);
for(int i=0;i<n-1;i++){
for(int j=i+1;j<n;j++){
cout<<a[i]<<" - "<<a[j]<<" = "<<a[i]-a[j]<<endl;
if(abs(a[i]-a[j]) == 2)
c++;
}
}
cout<<c<<endl;
return 0; }