Summary Ranges

class Solution {
public:
    vector<string> rangeSummary(vector<int>& inputArray) {
        vector<string> result;
    
        for (int j = 0; j < inputArray.size(); j++) {
            int startNum = inputArray[j];
            // Loop to find consecutive numbers sequence
            while (j + 1 < inputArray.size() && inputArray[j] + 1 == inputArray[j + 1]) {
                j++;
            }
    
            if (startNum != inputArray[j]) {
                result.push_back(to_string(startNum) + "->" + to_string(inputArray[j]));
            } else {
                result.push_back(to_string(startNum));
            }
        }
    
        return result;
    }
};

The provided C++ code defines a solution to construct summary ranges from a given vector of integers. The function rangeSummary within the Solution class processes an input vector to concisely represent contiguous sequences. Here's how the code tackles the problem:

1. Initialize an empty vector result to store the final sequence of ranges.
2. Iterate through the input vector using a for loop.
3. Assign the current element of the vector to startNum. This variable marks the beginning of a potential sequence.
4. Use a nested while loop to identify continuous consecutive sequences by checking if two successive numbers differ by exactly one. If true, increment the index j to extend the current range.
5. At the end of the while loop, check if startNum is different from the current element pointed by j. If they differ, it means a range has been identified and is thus added to result in the format startNum->currentNumber. If not, the number stands alone and is added to result as a single element string.
6. Repeat the steps until the entire array has been processed.
7. Return the vector containing all the summarized ranges.

This function directly processes the input array, utilizing a combination of simple arithmetic and vector operations to build the output. It efficiently groups consecutive numbers into ranges, thereby compressing the information into a more readable format.

class Solution {
    public List<String> findRanges(int[] numbers) {
        List<String> rangeList = new ArrayList<>();
    
        for (int i = 0; i < numbers.length; i++) {
            int begin = numbers[i];
            // Loop to find consecutive integers.
            while (i + 1 < numbers.length && numbers[i] + 1 == numbers[i + 1]) {
                i++;
            }
    
            if (begin != numbers[i]) {
                rangeList.add(begin + "->" + numbers[i]);
            } else {
                rangeList.add(String.valueOf(begin));
            }
        }
    
        return rangeList;
    }
}

The given Java code solves the problem of finding and summarizing consecutive ranges in an array of integers. Here's how the code functions:

• Initialize an ArrayList named rangeList to store the resulting ranges as strings.
• Traverse through the array of numbers using a for loop. For each number, check if it starts a new range by comparing it to the next number in the array.
• If the current number and the next one are consecutive, use a while loop to continue to the end of this consecutive sequence.
• Check if the range consists of more than one number:
  • If so, format the range as "begin->end" and add to rangeList.
  • If the current number does not have any consecutive followers, add it directly as a string to rangeList.
• Finally, return the rangeList.

This approach ensures each number or consecutive range is correctly identified and formatted, leveraging loop control and list operations efficiently.

class Solution:
    def collateIntervals(self, numbers: List[int]) -> List[str]:
        collected_ranges = []     
        index = 0 
            
        while index < len(numbers): 
            start_point = numbers[index]  
            while index + 1 < len(numbers) and numbers[index] + 1 == numbers[index + 1]: 
                index += 1 
                
            if start_point != numbers[index]: 
                collected_ranges.append(f"{start_point}->{numbers[index]}")
            else: 
                collected_ranges.append(str(numbers[index]))
                
            index += 1
    
        return collected_ranges

In the provided Python program, you process a list of integers to generate a list of summary ranges. Here's a breakdown of how this solution operates:

• A list named collected_ranges is initialized to store the resulting summary ranges as strings.
• You initialize index to zero to traverse through the list, numbers.
• A while loop runs as long as index is less than the length of the list. Inside this loop:
  • You set the start_point to the current number at the position index.
  • Another while loop checks if the current number is sequentially followed by the next number (i.e., current number + 1 equals the next number). If true, index is incremented to extend the current range.
  • After determining the end of a range, you compare start_point with the current number at index. If they are different, it implies a range which is then appended to collected_ranges in the format "start->end". If they are the same, only a single number is appended as a string.
  • index is incremented to move to the next potential range or number.

Final output, collected_ranges, is a list of strings, each representing either a single number or a range of numbers in your input list. This allows you to clearly identify which numbers or sequences follow directly after one another.