碰巧遇见他 怎么说

happen to meet sb. 碰巧遇见

如果为了突出巧遇,偶遇
run into sb 更合适,突出那个巧,那个偶然

For instance:

I run into Mary early this morning, and she was with another man ,which is so depressing.

I've happened to meet him.

run across him

happen to meet him