Minor fix

Author: xyzqm

content/6_Advanced/Slope_Trick.mdx

@@ -365,7 +365,7 @@ fertilizer), so it's not too hard to guess that slope trick is applicable.
 
 ### Slow Solution
 
-Let $dp[i][j]$ equal the number of ways to move dirt around the first $i$
+Let $dp[i][j]$ equal the minimum cost to move dirt around the first $i$
 flowerbeds such that the first $i-1$ flowerbeds all have the correct amount of
 dirt while the $i$-th flowerbed has $j$ extra units of dirt (or lacks $-j$ units
 of dirt if $j$ is negative). The answer will be $dp[N][0]$.