https://leetcode.com/problems/minimum-domino-rotations-for-equal-row/

minimum-domino-rotations-for-equal-row.js

var minDominoRotations = function(A, B) {
    
    const minRotationsToSetAllTo = (x) => {
        let aSame = 0;
        let bSame = 0;
        for(let i=0; i<A.length; i++){
            if(A[i] !== x){
                if(B[i] === x) aSame++;
                else aSame = Infinity;
            }
            
            if(B[i] !== x){
                if(A[i] === x) bSame++;
                else bSame = Infinity;
            }
            
            if(aSame === Infinity && bSame === Infinity) break;
        }
        return Math.min(aSame, bSame);
    };
    
    const minRotations = Math.min(
        minRotationsToSetAllTo(A[0]),
        minRotationsToSetAllTo(B[0])
    );
    return minRotations === Infinity ? -1 : minRotations;
};