> For the complete documentation index, see [llms.txt](https://ucan.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ucan.gitbook.io/notes/76.-minimum-window-substring.md).

# 76. Minimum Window Substring

{% hint style="info" %}
Sliding Window
{% endhint %}

```java
class Solution {
    public String minWindow(String s, String t) {
        int[] memo = new int[128];
        for(int i = 0; i < t.length(); i++){
            memo[t.charAt(i)]++;
        }
        
        int count = t.length(), left = 0, right = 0;
        int p1=0, p2=Integer.MAX_VALUE;
        while(right<s.length()){
            // first check if the char at right is in t
            // then check if count == 0 
            // (means the window contians all characters in t)
            if(memo[s.charAt(right++)]-- >0) count--;
            while(count == 0){
                if(right-left<p2-p1) {
                    // left is inclusive
                    p1=left;
                    // right is exclusive because of right++
                    p2=right;
                }
                if (memo[s.charAt(left++)]++==0) count++;
            }
        } 
        return p2==Integer.MAX_VALUE ? "" : s.substring(p1, p2);
    }
}
```