# 2103. Rings and Rods
###### tags: `Leetcode` `Easy`
Link: https://leetcode.com/problems/rings-and-rods/description/
## Code

class Solution {
    public int countPoints(String rings) {
        //0 B 1 R 2 G
        boolean[][] colors = new boolean[10][3];
        for(int i=0; i+1<rings.length(); i+=2){
            int rod = rings.charAt(i+1)-'0';
            char c = rings.charAt(i);
            if(c=='B' && !colors[rod][0]) colors[rod][0]=true;
            else if(c=='R' && !colors[rod][1]) colors[rod][1]=true;
            else if(c=='G' && !colors[rod][2]) colors[rod][2] = true;
        }
        int ans = 0;
        for(int i=0; i<10; i++){
            if(colors[i][0] && colors[i][1] && colors[i][2]) ans++;
        }
        return ans;
    }
}

Bit Manipulation

class Solution {
    public int countPoints(String rings) {
        //0 B 1 R 2 G
        int[] colors = new int[10];
        for(int i=0; i+1<rings.length(); i+=2){
            int rod = rings.charAt(i+1)-'0';
            char c = rings.charAt(i);
            if(c=='B' && (colors[rod]&1)==0) colors[rod]+=1;
            else if(c=='R' && ((colors[rod]>>1)&1)==0) colors[rod]+=(1<<1);
            else if(c=='G' && ((colors[rod]>>2)&1)==0) colors[rod]+=(1<<2);
        }
        int ans = 0;
        int full = 1+(1<<1)+(1<<2);
        for(int i=0; i<10; i++){
            if(colors[i]==full) ans++;
        }
        return ans;
    }
}