Word Game 2

function processData(input) {
    var arr = input.split("\n");
    var start = arr[0];
    var target = arr[1];

    var longest = 0;
    var L = new Array(start.length);
    for(var i=0; i<start.length; i++){
        L[i] = new Array(target.length);
    }

    for(var i=0; i<L.length; i++){
        for(var j=0; j<L[0].length; j++){
            if(start.charAt(i)==target.charAt(j)){
                if(i==0 || j==0){
                    L[i][j] = 1;
                }
                else{
                    L[i][j] = L[i-1][j-1] + 1;
                }
                if(L[i][j] > longest){
                    longest = L[i][j];
                }
            }
            else{
                L[i][j] = 0;
            }
        }
    }

    var shortestLength = start.length + target.length - 2*longest;
    var bruteForceLength = start.length + target.length;

    var probabilities = [0,0,1/36,2/36,3/36,4/36,5/36,6/36,5/36,4/36,3/36,2/36,1/36];
    var possibles = [false,false];

    for(var i=2; i<=12; i++){
        if(i>=bruteForceLength || (i>=shortestLength && (i-shortestLength)%2==0)){
            possibles.push(true);
        }
        else{
            possibles.push(false);
        }
    }
    var sum = 0;
    for(var i=2; i<=12; i++){
        if(possibles[i]){
            sum+=probabilities[i];
        }
    }
    console.log(sum.toFixed(4));

}

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});