1056-ConfusingNumber.go

package main

// 1056. Confusing Number
// A confusing number is a number that when rotated 180 degrees becomes a different number with each digit valid.
// We can rotate digits of a number by 180 degrees to form new digits.
//     When 0, 1, 6, 8, and 9 are rotated 180 degrees, they become 0, 1, 9, 8, and 6 respectively.
//     When 2, 3, 4, 5, and 7 are rotated 180 degrees, they become invalid.

// Note that after rotating a number, we can ignore leading zeros.
// For example, after rotating 8000, we have 0008 which is considered as just 8.
// Given an integer n, return true if it is a confusing number, or false otherwise.

// Example 1:
// <img src="https://assets.leetcode.com/uploads/2019/03/23/1268_1.png" />
// Input: n = 6
// Output: true
// Explanation: We get 9 after rotating 6, 9 is a valid number, and 9 != 6.

// Example 2:
// <img src="https://assets.leetcode.com/uploads/2019/03/23/1268_2.png" />
// Input: n = 89
// Output: true
// Explanation: We get 68 after rotating 89, 68 is a valid number and 68 != 89.

// Example 3:
// <img src="https://assets.leetcode.com/uploads/2019/03/26/1268_3.png" />
// Input: n = 11
// Output: false
// Explanation: We get 11 after rotating 11, 11 is a valid number but the value remains the same, thus 11 is not a confusing number
 
// Constraints:
//     0 <= n <= 10^9

import "fmt"

func confusingNumber(n int) bool {
    if n == 0 {
        return false
    }
    // When 0, 1, 6, 8, and 9 are rotated 180 degrees, they become 0, 1, 9, 8, and 6 respectively.
    m := map[int]int{ 0:0, 1:1, 6:9, 8:9, 9:6 }
    x, y := 0, n
    for n > 0 {
        t := n % 10
        if v,ok := m[t]; ok {
            x = x * 10 + v
        } else {// When 2, 3, 4, 5, and 7 are rotated 180 degrees, they become invalid.
            return false
        }
        n /= 10
    }
    return x != y
}

func main() {
    // Explanation: We get 9 after rotating 6, 9 is a valid number, and 9 != 6.
    fmt.Println(confusingNumber(6)) // true
    // Explanation: We get 68 after rotating 89, 68 is a valid number and 68 != 89.
    fmt.Println(confusingNumber(98)) // true
    // Explanation: We get 11 after rotating 11, 11 is a valid number but the value remains the same, thus 11 is not a confusing number
    fmt.Println(confusingNumber(11)) // false
}