update

src/P2822/P2822_prefix.cpp

@@ -16,7 +16,7 @@ static void init(){
             c[i][j] = (c[i-1][j-1] + c[i-1][j])%k;
         }
     }
-    for(ull i = 2;i<max_n;i++){ //t被修改
+    for(ull i = 2;i<max_n-1;i++){ //注意这里是max_n-1
         for(ull j{1};j<=i;j++){
             prefix[i][j] = prefix[i-1][j]+prefix[i][j-1]-prefix[i-1][j-1] + (c[i][j]==0?1:0);
         }