# Consecutive Ones - Amazon Top Interview Questions

### Problem Statement :

```You are given a list of integers nums which contains at least one 1. Return whether all the 1s appear consecutively.

Constraints

1 ≤ n ≤ 100,000 where n is the length of nums

Example 1

Input

nums = [0, 1, 1, 1, 2, 3]

Output
True

Explanation

All the 1s appear consecutively here in the middle.```

### Solution :

```                        ```Solution in C++ :

bool solve(vector<int>& nums) {
for (int i = 0, prev = -1; i < nums.size(); i++) {
if (nums[i] == 1) {
if (prev != -1 && i - prev > 1)
return false;
else
prev = i;
}
}
return true;
}```
```

```                        ```Solution in Java :

import java.util.*;

class Solution {
public boolean solve(int[] nums) {
int f = -1;
int l = -1;
int c = 0;
for (int i = 0; i < nums.length; i++) {
if (nums[i] == 1) {
if (f == -1) {
f = i;
}
l = i;
c++;
}
}
return (c == l - f + 1);
}
}```
```

```                        ```Solution in Python :

class Solution:
def solve(self, nums):
"""
0 means never seen
1 means currently seeing
2 means has finished seeing
"""
for x in nums:
if x == 1:
return False
return True```
```

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