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#2103 - Rings and Rods
Problem Description
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 the ith ring's color ('R', 'G', 'B').
- The second character of the ith pair denotes the rod that the ith 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.
Solution
/**
* @param {string} rings
* @return {number}
*/
var countPoints = function(rings) {
const map = new Map();
for (let i = 0; i < rings.length; i += 2) {
const color = rings[i];
const rod = rings[i + 1];
if (!map.has(rod)) map.set(rod, new Set());
map.get(rod).add(color);
}
let result = 0;
for (const colors of map.values()) {
if (colors.size === 3) result++;
}
return result;
};