如果使用start或者end作为map的key的话，很方便针对end或者start排序，但是测试数据中会有相同的end或者start，导致出现wrong anwser，后来使用vector<pair<int，int>>的方式记录，sort排序，终于过了
#include <iostream>
#include <map>
#include <vector>
#include <algorithm>

using namespace std; 

int dp[10000001] = {0};

bool cmp(pair<int, int> a, pair<int, int> b) {
	return a.first < b.first;
}

int main()
{
	int  N, M, R;
	scanf("%d %d %d" , &N, &M, &R);
	
	vector<pair<int, int> > endList;
	vector<pair<int, int> > timeList;
	
	int start, end, effiency;
	for (int i = 0; i < M; i++) {
		scanf("%d %d %d", &start, &end, &effiency);
		endList.push_back(make_pair(end, i));
		timeList.push_back(make_pair(start, effiency));
	} 

	sort(endList.begin(), endList.end(), cmp);
	
	for (vector<pair<int, int> >::iterator iter = endList.begin(); iter != endList.end(); iter++) {
		int prevDp;
		
		end = iter->first;
		start = timeList[iter->second].first;
		effiency = timeList[iter->second].second;
		
		if (start - R <= 0)
			prevDp = 0;
		else
			prevDp = dp[start-R];
			
		for (int i = end; i <= N; i++) {
			int e = prevDp + effiency;
			if (e > dp[i])
				dp[i] = e;
		}
		
	}
	
	printf("%d\n", dp[N]);
	return 0;
}