77
00:05:39,520 --> 00:05:41,520
另外一个就是循环

78
00:05:41,520 --> 00:05:45,520
如果怎么样

79
00:05:45,520 --> 00:05:47,520
就再做一遍

80
00:05:47,520 --> 00:05:49,520
如果还满足条件就再做一遍

81
00:05:49,520 --> 00:05:51,520
那就是循环

82
00:05:51,520 --> 00:05:53,520
循环的这个

83
00:05:53,520 --> 00:05:55,520
画法

84
00:05:55,520 --> 00:05:57,520
循环有两种

85
00:05:57,520 --> 00:05:59,520
一种是

86
00:05:59,520 --> 00:06:01,520
先判断

87
00:06:01,520 --> 00:06:03,520
第二种是

88
00:06:03,520 --> 00:06:05,520
至少做一遍

89
00:06:05,520 --> 00:06:07,520
然后再判断

90
00:06:07,520 --> 00:06:11,520
这个的话

91
00:06:11,520 --> 00:06:13,520
这个

92
00:06:13,520 --> 00:06:15,520
这个你看，这个对应的图

93
00:06:15,520 --> 00:06:17,520
比较好理解

94
00:06:17,520 --> 00:06:19,520
这个过来

95
00:06:19,520 --> 00:06:21,520
做一遍

96
00:06:21,520 --> 00:06:23,520
你看这里面

97
00:06:23,520 --> 00:06:25,520
这里面

98
00:06:25,520 --> 00:06:27,520
这是进来的

99
00:06:27,520 --> 00:06:29,520
也就是说，这个

100
00:06:29,520 --> 00:06:31,520
实际上是合并的点

101
00:06:31,520 --> 00:06:35,520
这个是合并的点

102
00:06:35,520 --> 00:06:37,520
它并不是决策点

103
00:06:37,520 --> 00:06:41,520
是把这边

104
00:06:41,520 --> 00:06:43,520
这边有令牌过来

105
00:06:43,520 --> 00:06:45,520
这边有没有不知道

106
00:06:45,520 --> 00:06:47,520
但是无所谓有没有

107
00:06:47,520 --> 00:06:49,520
这里有了，这两个合并

108
00:06:49,520 --> 00:06:51,520
过来

109
00:06:51,520 --> 00:06:53,520
所以它是有令牌的

110
00:06:53,520 --> 00:06:55,520
这个

111
00:06:55,520 --> 00:06:57,520
这个肯定要做一遍

112
00:06:57,520 --> 00:06:59,520
过来之后，你看这个

113
00:06:59,520 --> 00:07:01,520
这是进来的

114
00:07:01,520 --> 00:07:03,520
出去的，出去的

115
00:07:03,520 --> 00:07:05,520
这个才是

116
00:07:05,520 --> 00:07:07,520
才是条件

117
00:07:07,520 --> 00:07:09,520
条件在这里

118
00:07:11,520 --> 00:07:13,520
这是条件

119
00:07:13,520 --> 00:07:15,520
满足条件走这边

120
00:07:15,520 --> 00:07:17,520
不满足就终止了

121
00:07:17,520 --> 00:07:19,520
对吧

122
00:07:19,520 --> 00:07:21,520
这个是这个

123
00:07:21,520 --> 00:07:23,520
那

124
00:07:23,520 --> 00:07:25,520
第二个就是

125
00:07:25,520 --> 00:07:27,520
什么

126
00:07:27,520 --> 00:07:29,520
先判断

127
00:07:29,520 --> 00:07:31,520
我们看我们的图

128
00:07:31,520 --> 00:07:33,520
过来

129
00:07:33,520 --> 00:07:35,520
进来

130
00:07:35,520 --> 00:07:37,520
然后条件

131
00:07:37,520 --> 00:07:39,520
满足就做A1

132
00:07:39,520 --> 00:07:41,520
做A1之后

133
00:07:41,520 --> 00:07:43,520
你看，这个令牌释出来之后

134
00:07:43,520 --> 00:07:45,520
释放出来之后

135
00:07:45,520 --> 00:07:47,520
你看，这里过来

136
00:07:47,520 --> 00:07:49,520
它又回到这里来

137
00:07:49,520 --> 00:07:51,520
对不对

138
00:07:51,520 --> 00:07:53,520
实际上，也就是说这个

139
00:07:53,520 --> 00:07:55,520
这个菱形

140
00:07:55,520 --> 00:07:57,520
这有两个进入

141
00:07:57,520 --> 00:07:59,520
但是这个进

142
00:07:59,520 --> 00:08:01,520
这个进，它只发生一遍

143
00:08:01,520 --> 00:08:03,520
对不对

144
00:08:03,520 --> 00:08:05,520
这个过来以后

145
00:08:05,520 --> 00:08:07,520

146
00:08:07,520 --> 00:08:09,520
这个就没有了

147
00:08:09,520 --> 00:08:11,520
初始这个只发生一次

148
00:08:11,520 --> 00:08:13,520
然后这个令牌

149
00:08:13,520 --> 00:08:15,520
就被分叉

150
00:08:15,520 --> 00:08:17,520
过来的嘛，然后它得到令牌

151
00:08:17,520 --> 00:08:19,520
过来，过来

152
00:08:19,520 --> 00:08:21,520
所以这时候这个没有令牌了

153
00:08:21,520 --> 00:08:23,520
这地方令牌已经被它用掉了

154
00:08:23,520 --> 00:08:25,520
它没有再产生，令牌

155
00:08:25,520 --> 00:08:27,520
过这边来，这样

156
00:08:27,520 --> 00:08:29,520
假设条件满足

157
00:08:29,520 --> 00:08:31,520
不满足就完蛋了嘛

158
00:08:31,520 --> 00:08:33,520
就走了

159
00:08:33,520 --> 00:08:35,520
条件满足，就过来

160
00:08:35,520 --> 00:08:37,520
令牌从这里过来

161
00:08:37,520 --> 00:08:39,520
所以呢，它表面上是两个

162
00:08:39,520 --> 00:08:41,520
是两个进来，但其实这里只有一个进来

163
00:08:41,520 --> 00:08:43,520
对吧

164
00:08:43,520 --> 00:08:45,520
一个进来，然后就分叉

165
00:08:45,520 --> 00:08:47,520
只不过第一次的时候，是这个扮演的进来

166
00:08:47,520 --> 00:08:49,520
以后是这个来扮演

167
00:08:49,520 --> 00:08:51,520
以后是这个来扮演

168
00:08:51,520 --> 00:08:55,520
这样来

169
00:08:55,520 --> 00:08:59,520
这是

170
00:08:59,520 --> 00:09:01,520
这两种循环

171
00:09:01,520 --> 00:09:03,520
的画图

172
00:09:03,520 --> 00:09:05,520
那这里面

173
00:09:05,520 --> 00:09:07,520
有一个要注意的

174
00:09:07,520 --> 00:09:09,520
就是说，像这个，比如说，循环

175
00:09:09,520 --> 00:09:11,520
假设这个

176
00:09:11,520 --> 00:09:13,520
你看这里

177
00:09:13,520 --> 00:09:15,520
两个进来

178
00:09:15,520 --> 00:09:17,520
这样过来，合并

179
00:09:17,520 --> 00:09:19,520
这样过来

180
00:09:19,520 --> 00:09:21,520
假设

181
00:09:21,520 --> 00:09:23,520
不要这个呢

182
00:09:23,520 --> 00:09:25,520
不要这个点

183
00:09:25,520 --> 00:09:27,520
我直接画这里，这个不行

184
00:09:27,520 --> 00:09:29,520
为什么，你看这个是动作

185
00:09:29,520 --> 00:09:31,520
动作

186
00:09:31,520 --> 00:09:33,520
它就严格要求什么

187
00:09:33,520 --> 00:09:35,520
如果有多个入边

188
00:09:35,520 --> 00:09:37,520
那每个入边都要有令牌才可以

189
00:09:37,520 --> 00:09:39,520
但是它是等不到

190
00:09:39,520 --> 00:09:41,520
两个令牌的，为什么，因为

191
00:09:41,520 --> 00:09:43,520
这个令牌过来

192
00:09:43,520 --> 00:09:47,520
这个令牌是什么

193
00:09:47,520 --> 00:09:49,520
是由这边过来

194
00:09:49,520 --> 00:09:51,520
但是这边的令牌

195
00:09:51,520 --> 00:09:53,520
怎么来的，它是从这边过来

196
00:09:53,520 --> 00:09:55,520
满足条件又回来的

197
00:09:55,520 --> 00:09:57,520
所以呢，你这个令牌

198
00:09:57,520 --> 00:09:59,520
过不去，它就没有办法过来

199
00:09:59,520 --> 00:10:01,520
你的令牌要能够过去的话

200
00:10:01,520 --> 00:10:03,520
怎么样

201
00:10:03,520 --> 00:10:05,520
你这里面就要有令牌

202
00:10:05,520 --> 00:10:07,520
所以它就死在这里了

203
00:10:07,520 --> 00:10:09,520
也就是说，A1

204
00:10:09,520 --> 00:10:11,520
它不会执行的

205
00:10:11,520 --> 00:10:13,520
但这个不叫非法，因为

206
00:10:13,520 --> 00:10:15,520
没准你就是让它卡在这里

207
00:10:15,520 --> 00:10:17,520
它只是说卡在这里

208
00:10:17,520 --> 00:10:19,520
并不非法

209
00:10:19,520 --> 00:10:21,520

210
00:10:21,520 --> 00:10:23,520
这个也是一种形状

211
00:10:23,520 --> 00:10:25,520
就像围棋里面

212
00:10:25,520 --> 00:10:27,520
死棋一样，不能说

213
00:10:27,520 --> 00:10:29,520
死棋是非法的

214
00:10:29,520 --> 00:10:31,520
它就死在这里了

215
00:10:31,520 --> 00:10:35,520
所以呢，这里，你看这里

216
00:10:35,520 --> 00:10:37,520
这里

217
00:10:37,520 --> 00:10:39,520
就不需要，因为这是合并点

218
00:10:39,520 --> 00:10:41,520
两个

219
00:10:41,520 --> 00:10:43,520
把这边令牌

220
00:10:43,520 --> 00:10:45,520
合成一个

221
00:10:45,520 --> 00:10:47,520
不管有没有

222
00:10:47,520 --> 00:10:49,520
有就有，没有就没有

223
00:10:49,520 --> 00:10:51,520
合成一个

224
00:10:55,520 --> 00:10:57,520
这是决策点

225
00:10:57,520 --> 00:11:01,520
下面

226
00:11:01,520 --> 00:11:03,520
我们用这个决策点来做一个题

227
00:11:03,520 --> 00:11:05,520
这个

228
00:11:05,520 --> 00:11:07,520
案例描述里面有这么一句话

229
00:11:07,520 --> 00:11:09,520
如果奖品是实物

230
00:11:09,520 --> 00:11:11,520
首先要抽奖了

231
00:11:11,520 --> 00:11:13,520
用这个软件抽奖

232
00:11:13,520 --> 00:11:15,520
看案例描述里面

233
00:11:15,520 --> 00:11:17,520
有一个抽奖的动作

234
00:11:17,520 --> 00:11:19,520
抽奖，如果奖品是实物，就这样

235
00:11:19,520 --> 00:11:21,520
用活动图

236
00:11:23,520 --> 00:11:25,520
把这个画出来

237
00:11:25,520 --> 00:11:27,520
把这个过程画出来

238
00:11:27,520 --> 00:11:29,520
泳道可以不用画

239
00:11:29,520 --> 00:11:31,520
比如说，这个是老师干的

240
00:11:31,520 --> 00:11:33,520
这是学生干的

241
00:11:33,520 --> 00:11:35,520
这是抽奖软件干的

242
00:11:35,520 --> 00:11:37,520
这微信干的

243
00:11:37,520 --> 00:11:39,520
这不用画

244
00:11:39,520 --> 00:11:41,520
你就说干了什么就行了

245
00:11:41,520 --> 00:11:43,520
是哪个系统干的，泳道不用画，还没讲