2103. 环和杆

2103. 环和杆

• 难度: easy
• 原始链接: https://leetcode.cn/problems/rings-and-rods
• 标签: 位运算

解法一: 位运算

go

func countPoints(rings string) int {
    flag := 0
    length := len(rings)
    for i := 1; i < length; i += 2 {
        shift := 0
        if rings[i - 1] == 'R' {
            shift = 1
        } else if rings[i - 1] == 'G' {
            shift = 1 << 1
        } else if rings[i - 1] == 'B' {
            shift = 1 << 2
        }
        flag |= shift << (int(rings[i] - '0') * 3)
    }
    ans := 0
    for flag != 0 {
        if (flag & 7) == 7 {
            ans++
        }
        flag >>= 3
    }
    return ans
}