应用实例九：概率树状图生成器知识点：第二十五章《概率初步》—— 用列举法求概率。功能：解决“连续抛硬币”或“摸球”问题。学生设置事件（如抛2次硬币），应用自动生成树状图，高亮显示所有可能结果，并计算特定事件的概率。interface TreeNode { path: string level: number isHeads: boolean } @Entry @Component struct ProbabilityTree { @State private steps: number = 2 @State private results: string[] = [] @State private treeNodes: TreeNode[] = [] @State private targetHeadsCount: number = 2 @State private totalOutcomes: number = 0 @State private favorableOutcomes: number = 0 @State private showTree: boolean = false build() { Column() { Text('🌳 用列举法求概率') .