var numDecodings = function(s) {
if (s.length === 0) return 0;
const N = s.length;
const dp = Array(N+1).fill(0);
dp[0] = 1;
dp[1] = s[0] === '0' ? 0 : 1;
for (let i = 2; i <= N; i++) {
if (s[i-1] !== '0') {
console.log(i,dp[i],dp[i-1])
dp[i] = dp[i] + dp[i-1];
}
if (s[i-2] === '1' || s[i-2] === '2' && s[i-1] <= '6') {
dp[i] = dp[i] + dp[i-2];
}
}
return dp[N];
};
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