# 8)Smallest window in a string containing all the characters of another string -(sliding window | variable size)

Given two strings S and P. Find the smallest window in the S consisting of all the characters of P.

Example 1:

```
Input:
S = "timetopractice"
P = "toc"
Output:
toprac
Explanation: "toprac" is the smallest
substring in which "toc" can be found.
```

Example 2:

```
Input:
S = "zoomlazapzo"
P = "oza"
Output:
apzo
Explanation: "apzo" is the smallest
substring in which "oza" can be found.
```

**c++ implementation:**

**string minWindow(string a, string p)
{
int n=a.length();
int m=p.length();
unordered_map<char,int>mp;
for(int i=0;i<m;i++)
mp[p[i]]++;
int count=mp.size();
int i=0;int j=0; int start=0;
int len=INT_MAX;
while(j<n)
{
mp[a[j]]--;
if(mp[a[j]]==0)
count--;
if (count == 0) {
while (count == 0)
{
if (len > j - i + 1) {
len = min(len, j - i + 1);
start = i;
}
mp[a[i]]++;
if (mp[a[i]] > 0)
count++;
i++;
}
}
j++;
}
if (len != INT_MAX)
return a.substr(start, len);
else
return "";
}**

**Time Complexity:**O(n)

**space Complexity:**O(n)