Weighted Merge Interval - Google Top Interview Questions

                        Solution in C++ :

vector<vector<int>> solve(vector<vector<int>>& intervals) {
    map<int, int> mp;
    for (auto& i : intervals) {
        mp[i[0]] += i[2];
        mp[i[1] + 1] -= i[2];
    }
    int sum = 0;
    int mx = 0;
    for (auto& [k, v] : mp) {
        sum += v;
        mx = max(sum, mx);
    }
    sum = 0;
    vector<vector<int>> ans;
    for (auto it = mp.begin(); it != prev(mp.end()); it++) {
        sum += it->second;
        int me = it->first;
        int him = next(it)->first;
        if (sum == mx) {
            ans.push_back({me, him - 1});
        }
    }
    vector<vector<int>> res;
    for (auto& i : ans) {
        if (!res.empty() && res.back()[1] == i[0] - 1) {
            res.back()[1] = i[1];
        } else {
            res.push_back(i);
        }
    }
    return res;
}
                    

                        Solution in Java :

import java.util.*;

class Solution {
    public int[][] solve(int[][] n) {
        int N = n.length;
        E[] events = new E[2 * N];
        for (int i = 0; i < N; i++) {
            events[i] = new E(n[i][0], 0, n[i][2]);
            events[i + N] = new E(n[i][1], 1, n[i][2]);
        }
        Arrays.sort(events);

        // find the maximum weight
        int maxw = 0;
        int curw = 0;
        for (E e : events) {
            if (e.type == 0)
                curw += e.w;
            else
                curw -= e.w;
            maxw = Math.max(maxw, curw);
        }

        ArrayList<int[]> ans = new ArrayList<int[]>();
        int w = 0;
        int last = Integer.MIN_VALUE;
        for (E e : events) {
            if (e.type == 0) {
                w += e.w;
            } else {
                if (w == maxw)
                    ans.add(new int[] {last, e.t});
                w -= e.w;
            }
            last = e.t;
        }

        ArrayList<int[]> merged = new ArrayList<int[]>();
        int s = ans.get(0)[0];
        int e = ans.get(0)[1];
        for (int i = 1; i < ans.size(); i++) {
            if (ans.get(i)[0] == e + 1) {
                e = ans.get(i)[1];
            } else {
                merged.add(new int[] {s, e});
                s = ans.get(i)[0];
                e = ans.get(i)[1];
            }
        }
        merged.add(new int[] {s, e});

        return convert(merged);
    }

    public int[][] convert(ArrayList<int[]> arr) {
        int[][] ret = new int[arr.size()][2];
        for (int i = 0; i < arr.size(); i++) ret[i] = arr.get(i);
        return ret;
    }

    static class E implements Comparable<E> {
        int t;
        int type;
        int w;
        public E(int t, int type, int w) {
            this.t = t;
            this.type = type;
            this.w = w;
        }

        public int compareTo(E e) {
            if (t != e.t)
                return t - e.t;
            else
                return type - e.type;
        }
    }
}
                    

                        Solution in Python : 
                            
class Solution:
    def merge(self, intervals):
        intervals.sort(key=lambda x: x[0])

        merged = []
        for interval in intervals:
            if not merged or merged[-1][1] < interval[0] - 1:
                merged.append(interval)
            else:
                merged[-1][1] = max(merged[-1][1], interval[1])

        return merged

    def solve(self, intervals):
        events = []
        for start, end, weight in intervals:
            events.append([start, weight, 0])
            events.append([end + 1, -weight, 1])

        events = sorted(events, key=lambda e: (e[0], -e[2]))

        highest = float("-inf")
        total = 0
        for time, weight, event in events:
            total += weight
            highest = max(highest, total)

        res, total = [], 0
        during, left = False, -1

        for time, weight, event in events:
            total += weight
            if total == highest:
                during, left = True, time
            elif during:
                res.append([left, time - 1])
                during = False
        if during:
            res.append([left, events[-1][0] - 1])
        return self.merge(res)