[Leet Code] Rings and Rods
Leetcode: https://leetcode.com/problems/rings-and-rods/
Problem:
There are n
rings and each ring is either red, green, or blue. The rings are distributed across ten rods labeled from 0
to 9
.
You are given a string rings
of length 2n
that describes the n
rings that are placed onto the rods. Every two characters in rings
forms a color-position pair that is used to describe each ring where:
- The first character of the
ith
pair denotes theith
ring's color ('R'
,'G'
,'B'
). - The second character of the
ith
pair denotes the rod that theith
ring is placed on ('0'
to'9'
).
For example, "R3G2B1"
describes n == 3
rings: a red ring placed onto the rod labeled 3, a green ring placed onto the rod labeled 2, and a blue ring placed onto the rod labeled 1.
Return the number of rods that have all three colors of rings on them.
Example 1:
Input: rings = "B0B6G0R6R0R6G9"
Output: 1
Explanation:
- The rod labeled 0 holds 3 rings with all colors: red, green, and blue.
- The rod labeled 6 holds 3 rings, but it only has red and blue.
- The rod labeled 9 holds only a green ring.
Thus, the number of rods with all three colors is 1.
Example 2:
Input: rings = "B0R0G0R9R0B0G0"
Output: 1
Explanation:
- The rod labeled 0 holds 6 rings with all colors: red, green, and blue.
- The rod labeled 9 holds only a red ring.
Thus, the number of rods with all three colors is 1.
Example 3:
Input: rings = "G4"
Output: 0
Explanation:
Only one ring is given. Thus, no rods have all three colors.
Constraints:
rings.length == 2 * n
1 <= n <= 100
rings[i]
wherei
is even is either'R'
,'G'
, or'B'
(0-indexed).rings[i]
wherei
is odd is a digit from'0'
to'9'
(0-indexed).
Solution:
func countPoints(rings string) int {
hashMap := make(map[string][]string)
counter := 0
for i := 0; i < len(rings); i+= 2{
letter := string(rings[i])
number := string(rings[i+1])
hashMap[number] = append(hashMap[number], letter)
}
fmt.Println(hashMap)
for number := range hashMap{
if len(unique(hashMap[number])) == 3{
counter += 1
}
}
return counter
}func unique(intSlice []string) []string {
keys := make(map[string]bool)
list := []string{}
for _, entry := range intSlice {
if _, value := keys[entry]; !value {
keys[entry] = true
list = append(list, entry)
}
}
return list
}