content: package codingquestions.leetcode;
  import java.util.*;
  /*
  611. Valid Triangle Number
  Solved
  Medium
  Topics
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  Given an integer array nums, return the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.
  
   
  
  Example 1:
  
  Input: nums = [2,2,3,4]
  Output: 3
  Explanation: Valid combinations are: 
  2,3,4 (using the first 2)
  2,3,4 (using the second 2)
  2,2,3
  Example 2:
  
  Input: nums = [4,2,3,4]
  Output: 4
   
  
  Constraints:
  
  1 <= nums.length <= 1000
  0 <= nums[i] <= 1000
  */
  class ValidTriangleNumber {
      public int triangleNumber(int[] nums) {
          Arrays.sort(nums);
  
          int res = 0;
          for(int i = 0; i < nums.length; i++){
              int r = i;
              for(int l = i + 1; l < nums.length; l++){
                  r = Math.max(r, l + 1);
                  
                  while(r < nums.length && nums[i] + nums[l] > nums[r])
                      r++;
                  
                  r--;
                  if(l < r)
                      res += (r - l);
              }
          }
  
          return res;
      }
  }
  