#### Approach #1

**JavaScript**

```
var plusOne = function(digits) {
var len = digits.length;
for(var i=len-1;i>=0;i--){
if(digits[i]<9){
digits[i] = digits[i]+1;
return digits;
} else {
digits[i] = 0;
}
}
digits.unshift(1);
return digits;
};
```

**Complexity Analysis**

- Time complexity : O(n)