Len, with 10 points, was the only Terrapin to score in double figures. Maryland led for much of the game but needed Len's basket to end NC State's 10-game winning streak.
Maryland (14-3, 2-2 Atlantic Coast Conference) has won 10 of 11 against the Wolfpack (14-3, 3-1), including five in a row at home.
Down 45-43, the Wolfpack pulled even on a follow-shot by Richard Howell and took their first lead on a 3-pointer by Scott Wood with 4:37 to go. But NC State never found its shooting touch - Wood finished 3 for 13, including 3 for 11 from beyond the arc.
Maryland led 30-21 early in the second half before Brown made a pair of baskets - including a driving dunk - during a 9-2 run that cut the margin to one point.
James Padgett then scored for the Terrapins and Jake Layman popped a 3-pointer to make it 37-30. Minutes later, a 3-pointer by Howard put Maryland ahead 40-31, and a driving layup by teammate Dez Wells made it a 10-point game.
The Wolfpack went 6½ minutes without a basket before a driving layup by Leslie cut the deficit to 42-35. That was part of an 8-0 spurt that got NC State to 42-40.
A horrid first half ended with Maryland leading 22-16 despite shooting 30 percent, going 0 for 6 from 3-point range and committing seven turnovers.
The Wolfpack needed more than seven minutes before getting onto the scoreboard and shot 23 percent (7 for 31) in its lowest-scoring half of the season.
Maryland got off a solid start, getting two baskets apiece from Seth Allen and Shaquille Cleare in going up 10-0. The Wolfpack opened 0 for 6 with three turnovers.
Howell ended NC State's scoring drought with a layup at the 13:52 mark, and then the Wolfpack missed their next six shots. Maryland also went cold, missing 16 straight field-goal tries over a span of nearly 12 minutes. Howard snapped the dry spell with a driving layup to put the Terrapins ahead 16-13.