原始数组
arr = [
  {id:1,name:'张三'},
  {id:1,name:'李四'},
  {id:1,name:'王五'},
  {id:2,name:'赵六'},
  {id:2,name:'田七'},
]

预期结果
 arr=[
    {id:1,name:'王五'},
    {id:2,name:'田七'},
 ]

根据id去重，保留最后一个元素，使用最简单的方法怎么实现？？？