擅长:python、mysql、java
<pre><code>str_='1a1b1c1d3e3e3e1f1g2h2h1i1j1k1l1m1n4o4o4o4o1p1q2r2r1s2t2t2u2u1v1w1x1y1z'
seen = set()
result = []
n=2
for i in range(0,len(str_),n):
item=str_[i:i+n]
if item not in seen:
seen.add(item)
result.append(item)
</code></pre>