Minimum Window Substring

"ADOBEC" contains A, B, and C -- length 6. But is that the shortest window, or is there something shorter hiding later in the string?

The Gap

Given s = "ADOBECODEBANC" and t = "ABC", find the shortest substring of s containing all characters of t. Starting from index 0, where do you think the first valid window ENDS?

A
0
D
1
O
2
B
3
E
4
C
5
O
6
D
7
E
8
B
9
A
10
N
11
C
12