min-domino-rotation-equal-row.js

// 1007. Minimum Domino Rotations For Equal Row
// In a row of dominoes, A[i] and B[i] represent the top and bottom halves of the ith domino.
// (A domino is a tile with two numbers from 1 to 6 - one on each half of the tile.)

// We may rotate the ith domino, so that A[i] and B[i] swap values.

// Return the minimum number of rotations so that all the values in A are the same,
// or all the values in B are the same.

// If it cannot be done, return -1.

// Example 1:

// Input: A = [2,1,2,4,2,2], B = [5,2,6,2,3,2]
// Output: 2
// Explanation: 
// The first figure represents the dominoes as given by A and B: before we do any rotations.
// If we rotate the second and fourth dominoes, we can make every value in the top row equal to 2,
// as indicated by the second figure.

// Example 2:
// Input: A = [3,5,1,2,3], B = [3,6,3,3,4]
// Output: -1
// Explanation: 
// In this case, it is not possible to rotate the dominoes to make one row of values equal.
 
// Constraints:

// 2 <= A.length == B.length <= 2 * 104
// 1 <= A[i], B[i] <= 6

/**
 * @param {number[]} A
 * @param {number[]} B
 * @description time,space complexity is O(n), O(1)
 * @return {number}
 */
var minDominoRotations = function(A, B) {
    let res =  Math.min(equalRowChecker(A,B,A[0]), 
                        equalRowChecker(A,B,B[0]),
                        equalRowChecker(B,A,B[0]),
                        equalRowChecker(B,A,A[0]))  
    if(res == Infinity) return -1
    return res
    
    function equalRowChecker(A,B,v){
        let count  = 0
        for(let i = 0; i < A.length; i++){
            if(!(A[i] == v || B[i] == v)){
                count = Infinity
                break  
            } 
            if(A[i] != v && B[i] == v){
                count++
            }   
        }
        return count
    }
};