1. A method for identifying hotspot areas in a layout, the method comprising: receiving the layout and a via range pattern which indicates one or more vias; generating a via-free range pattern from the via range pattern by removing the one or more vias from the via range pattern; performing range-pattern matching (RPM) on the layout based on the via-free range pattern; identifying at least one candidate area in the layout based on an RPM result; determining, by one or more computers, whether the candidate area contains a via that matches the via in the via range pattern; and producing a result to indicate whether the candidate area is a hotspot based on the determination.