Files: ======================== doughnut : The data set of doughnut shape. doughnut.png : A preview of doughnut shape. Smile : The data set of smile shape. Smile.png : A preview of smile shape. Star : The data set of star shape. Star.png : A preview of star shape. U-Shape : The data set of u-shape shape. U-Shape.png : A preview of u-shape shape.
Format of dataset: ======================== For example, a data has n nodes and m edges.  line : Node count.  - [n+1] line : Node index, x position, y position. Remark: the x and y positions are within [0,1]. [n+2] line : Edge count. [n+3] - END line : start node of edge, end node of edge.