Fix threshold initialization in PRank and OAPBPM (#741)

Author: ishii-norimi

lib/model/oapbpm.js

@@ -45,7 +45,7 @@ export default class OAPBPM {
 					this._b[j].splice(
 						this._b[j].length - 1,
 						0,
-						...Array(this._min + this._b[j].length - y[k] + 1).fill(this._b[j][this._b[j].length - 2])
+						...Array(y[k] - (this._min + this._b[j].length) + 1).fill(this._b[j][this._b[j].length - 2])
 					)
 				}
 			}

lib/model/prank.js

@@ -34,7 +34,7 @@ export default class PRank {
 				this._b.splice(
 					this._b.length - 1,
 					0,
-					...Array(this._min + this._b.length - y[k] + 1).fill(this._b[this._b.length - 2])
+					...Array(y[k] - (this._min + this._b.length) + 1).fill(this._b[this._b.length - 2])
 				)
 			}