In this HackerEarth Smallest substring problem solution, you are given a string S that is made of lowercase English alphabets. Determine the length of the smallest substring that contains the maximum number of distinct characters.

## HackerEarth Smallest substring problem solution.

```#include<bits/stdc++.h>

using namespace std;

int check(int f[30], int mx){
int temp = 0;
for(int i=0; i<26; i++)if(f[i])temp++;
return (temp==mx);
}

int main(){
string str = ""; cin>>str;
int n = str.length();
int dist[30] = {0};
for(int i=0; i<n; i++)
dist[str[i]-'a'] = 1;
int mx = 0;
int ans = 1;
for(int i=0; i<26; i++)mx += dist[i];
int low = 1, high = n;
while(low <= high){
int mid = (low+high)/2;
int f[30]={0}, flag = 0;
for(int i=0; i<mid; i++)f[str[i]-'a']++;
for(int j=1; j<=n-mid; j++){
if(check(f, mx)){
flag = 1; break;
}
f[str[j-1]-'a']--;
f[str[j+mid-1]-'a']++;
}
if(check(f, mx))flag = 1;
if(flag){
ans = mid;
high = mid-1;
}
else low = mid+1;
}
cout<<ans<<endl;
return 0;
}```

### Second solution

```#include <bits/stdc++.h>

using namespace std;
int A[30], B[30];

int main(int argc, char* argv[])
{
if(argc == 2 or argc == 3) freopen(argv[1], "r", stdin);
if(argc == 3) freopen(argv[2], "w", stdout);
ios::sync_with_stdio(false);
string s;
int z = 0;
cin >> s;
assert(1 <= s.length() and s.length() <= 100000);
for (int i = 0; i < s.length(); i++) {
assert('a' <= s[i] and s[i] <= 'z');
if (A[s[i] - 'a'] == 0) z++;
A[s[i] - 'a']++;
}

int x = 0, y = 0, k = 0, ans;
while (k < z) {
if (B[s[y] - 'a'] == 0) k++;
B[s[y] - 'a']++;
while (x < y) {
if (B[s[x] - 'a'] == 1) break;
B[s[x] - 'a']--;
x++;
}
y++;
}
ans = y - x;
while (y < s.length()) {
B[s[y] - 'a']++;
while (x < y) {
if (B[s[x] - 'a'] == 1) break;
B[s[x] - 'a']--;
x++;
}
y++;
ans = min(ans, y - x);
}
cout << ans << endl;
return 0;
}```