/**

 * @param {string} s

 * @return {number}

 */

var numDecodings = function(s) {

    if(s.length == 0 || parseInt(s) == 0 || s[0] == '0' || s.indexOf('00') != -1){

        return 0

    }

    var ds = ""

    for(var i =0 ;i<s.length-1;i++){

        if(s[i] == 0){

            continue

        }

        if(s[i+1] != 0){

            ds += s[i]

        }

        else if(s[i] <='2'){

            ds += "A"

        }

        else{

            return 0

        }

    }

    if(s[s.length-1] != '0')

        ds += s[s.length-1]

    var dp = new Array(ds.length)

    dp[0] = 1

    if(ds[0] <='2' && ds[0] > '0' && ds[1] !='A'){

        if(ds[0] == 2 && ds[1] >='7'){

            dp[1] = 1

        }

        else{

            dp[1] = 2

        }

    }

    else{

        dp[1] = 1

    }

    for(var i = 2;i<ds.length;i++) {

        if (ds[i] == 'A') {

            dp[i] = dp[i - 1]

            continue

        }

        if (ds[i - 1] <= '2' && ds[i - 1] > 0 ) {

            if(ds[i-1] == '2' &&  ds[i] > '6'){

                dp[i] = dp[i - 1]

            }

            else{

                dp[i] = dp[i - 1] + dp[i - 2]

            }

        }

        else {

            dp[i] = dp[i - 1]

        }

    }

    //console.log(dp)

    return dp[ds.length-1]

};