Method add_edge

code/chapter08/word_ladder.rs:118–132

添加边

(&mut self, from: &T, to: &T, wt: u32)

    // 添加边
    fn add_edge(&mut self, from: &T, to: &T, wt: u32) {
        // 点不存在需要先添加
        if !self.contains(from) {
            let _fvert = self.add_vertex(from);
        }
        if !self.contains(to) {
            let _tvert = self.add_vertex(to);
        }

        self.edgenums += 1;
        self.vertices
            .get_mut(from)
            .unwrap()
            .add_neighbor(to.clone(), wt);
    }
}

// 根据单词及模式构建图