export function countPairsWithSum(nums: number[], target: number): number {
  /*con punteros*/
  il        = 0
  ir        = nums.length-1
  count     = 0
  while(il<ir){
    res = nums[il]+nums[ir]
    if(res == target){
      if(nums[il]==nums[ir]){
        zt = ir-il
        count+=parseInt(zt*(zt+1)/2)
        break
      }else{
        dup_right=1
        dup_left=1
        while(il<nums.length && nums[il]==nums[il+1]){
          dup_left++
          il++
        }
        while(ir>=0 && nums[ir]==nums[ir-1]){
          dup_right++
          ir--
        }
        count+=dup_left>0 && dup_right>0 ? dup_left*dup_right : Math.max(1,Math.max(dup_left,dup_right))
        il++
        ir--
      }
    }
    if(res>target){
      ir--
    }else if(res<target){
      il++
    }
  }

  return count
  /*sin punteros*/
  hash = {}
  rt   = 0
  for(let i=0;i<nums.length;i++){
    if(nums[i] in hash){
      rt+=hash[nums[i]]
    }
    let pre   = target-nums[i]
    hash[pre] = (hash[pre] ?? 0)+1

  }
  return rt
}