coupe-tools: fix xadj length

Author: hhirtz

coupe-metis/src/lib.rs

@@ -42,7 +42,7 @@ unsafe fn partition(
 
     // TODO make graph algorithms work over CsMatViewI instead of CsMatView
     // to avoid these conversions.
-    let xadj: Vec<usize> = slice::from_raw_parts(xadj, nvtxs)
+    let xadj: Vec<usize> = slice::from_raw_parts(xadj, nvtxs + 1)
         .iter()
         .map(|i| *i as usize)
         .collect();