<p>Given an integer array <code>nums</code>, return <em>the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,2,3,4]
<strong>Output:</strong> 3
<strong>Explanation:</strong> Valid combinations are: 
2,3,4 (using the first 2)
2,3,4 (using the second 2)
2,2,3
</pre>

<p><strong class="example">Example 2:</strong></p>

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

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
	<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>
</ul>

class Solution {
public:
    int triangleNumber(vector<int>& nums) {
        int count = 0;
        sort(nums.begin(), nums.end());

        for(int c = 2; c < nums.size(); c++){
            int a = 0, b = c-1;

            while(a < b){
                if(nums[a] + nums[b] > nums[c]){
                    count += (b - a);
                    b--;
                }else{
                    a++;
                }
            }
        }

        return count;

    }
};
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