Merge Intervals

Key Signals & Indicators

• Input is a list of coordinate pairs or intervals (start, end)
• Finding overlapping periods, scheduling, or range unions
• Requires sorting intervals before traversal

// C++ Merge Intervals Template
#include <vector>
#include <algorithm>

std::vector<std::vector<int>> mergeIntervals(std::vector<std::vector<int>>& intervals) {
    if (intervals.empty()) return {};
    
    // Sort intervals by start values
    std::sort(intervals.begin(), intervals.end());
    
    std::vector<std::vector<int>> merged;
    merged.push_back(intervals[0]);
    
    for (size_t i = 1; i < intervals.size(); ++i) {
        auto& last = merged.back();
        if (intervals[i][0] <= last[1]) {
            last[1] = std::max(last[1], intervals[i][1]); // Merge
        } else {
            merged.push_back(intervals[i]); // Append new non-overlapping
        }
    }
    return merged;
}