# 503. Next Greater Element II

## Problem Statement

<br>

Given a circular integer array `nums` (i.e., the next element of `nums[nums.length - 1]` is `nums[0]`), return *the **next greater number** for every element in* `nums`.

The **next greater number** of a number `x` is the first greater number to its traversing-order next in the array, which means you could search circularly to find its next greater number. If it doesn't exist, return `-1` for this number.

&#x20;

**Example 1:**

<pre><code><strong>Input: nums = [1,2,1]
</strong><strong>Output: [2,-1,2]
</strong>Explanation: The first 1's next greater number is 2; 
The number 2 can't find next greater number. 
The second 1's next greater number needs to search circularly, which is also 2.
</code></pre>

**Example 2:**

<pre><code><strong>Input: nums = [1,2,3,4,3]
</strong><strong>Output: [2,3,4,-1,4]
</strong></code></pre>

&#x20;

**Constraints:**

* `1 <= nums.length <= 104`
* `-109 <= nums[i] <= 109`

## Intuition

```
Approach:
Array has duplicates, So Store index in map rather than actual values
```

### Links

<https://leetcode.com/problems/next-greater-element-ii/description/>

### Video Links

### Approach 1:

```
```

{% code title="C++" lineNumbers="true" %}

```cpp
class Solution {
public:
    vector<int> nextGreaterElements(vector<int>& nums) {
        int n=nums.size();
        unordered_map<int, int>mp;
        stack<int> st;
        for(int i=0; i<2*n; i++) {
            while(!st.empty() and nums[st.top()] < nums[i%n]){
                mp[st.top()] = nums[i%n];
                st.pop();
            }
            st.push(i%n);
        }

        vector<int> ans;
        for(int i=0; i<n; i++){
            if(mp.find(i) != mp.end())
                ans.push_back(mp[i]);
            else
                ans.push_back(-1);
        }
            

        return ans;
    }
};
```

{% endcode %}

### Approach 2:

```
```

{% code title="C++" lineNumbers="true" %}

```cpp
```

{% endcode %}

### Approach 3:

```
```

{% code title="C++" lineNumbers="true" %}

```cpp
```

{% endcode %}

### Approach 4:

```
```

{% code title="C++" lineNumbers="true" %}

```cpp
```

{% endcode %}

### Similar Problems

###


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