go实现组内排序取前n

row_number

//分组排序取前n
//结构为 map[组id]map[组内每个值的id]排序的值   n为取前n
//返回：map[组id][]组内id
func aaa(arr map[int32]map[int32]int32, n int) (res map[int32][]int32) {
	type kv struct {
		id  int32
		val int32
	}
	res = make(map[int32][]int32)
	for groupId, groupVal := range arr {
		kvArr := make([]kv, 0, len(groupVal))
		for k, v := range groupVal {
			kvArr = append(kvArr, kv{id: k, val: v})
		}
		for k, v := range kvArr {
			value := v
			var j int32
			for j = int32(k - 1); j >= 0 && value.val > kvArr[j].val; j-- {
				kvArr[j+1] = kvArr[j]
			}
			kvArr[j+1] = value
		}
		l := len(kvArr)
		for kn := 0; kn < n; kn++ {
			if l <= kn {
				continue
			}
			res[groupId] = append(res[groupId], kvArr[kn].id)
		}
	}
	return res
}