Go: ///
// File:  0579.go
// Author: ymiyamoto
//
// Created on Mon Mar 19 18:46:50 2018
//
package main

import (
	"fmt"
)

var D, N int

type cloth struct {
	A, B, C int
}

func abs(a int) int {
	if a > 0 {
		return a
	}
	return -a
}

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

func main() {
	fmt.Scan(&D, &N)
	thermals := make([]int, D+1)

	for i := 1; i <= D; i++ {
		fmt.Scan(&thermals[i])
	}

	clothes := make([]cloth, N)
	for i := 0; i < N; i++ {
		fmt.Scan(&clothes[i].A, &clothes[i].B, &clothes[i].C)
	}

	dp := make([][]int, D+1)
	for i := range dp {
		dp[i] = make([]int, N)
	}

	for i := 1; i < D; i++ {
		for j := 0; j < N; j++ {
			for k := 0; k < N; k++ {
				t1 := thermals[i]
				t2 := thermals[i+1]
				if clothes[j].A <= t2 && t2 <= clothes[j].B && clothes[k].A <= t1 && t1 <= clothes[k].B {
					dp[i+1][j] = max(dp[i+1][j], dp[i][k]+abs(clothes[j].C-clothes[k].C))
				}
			}
		}
	}

	val := 0
	for _, v := range dp[D] {
		val = max(val, v)
	}

	fmt.Println(val)
}

C++: #include <iostream>
#include <cstdio>
#include <iomanip>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <utility>
#include <numeric>
#include <algorithm>
#include <functional>
#include <cctype>
#include <complex>
#include <string>
#include <sstream>
#include <fstream>
#include <cassert>
using namespace std;

//common
typedef int  i32;
typedef long long i64,ll;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii;
typedef long long ll; typedef vector<long long> vl; typedef pair<long long,long long> pll; typedef vector<pair<long long,long long> > vpll;
typedef vector<string> vs; typedef long double ld;

#define BR "\n"
#define ALL(c) (c).begin(),(c).end()
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define EACH(it,o) for(auto it = (o).begin(); it != (o).end(); ++it)
#define IN(l,v,r) ((l)<=(v) && (v)<(r))

//config
//#define NDEBUG
//#define INF 1<<30
//#define EPS 1e-8
//const ll MOD =100000007;

//debug
#ifdef NDEBUG
#define DUMP(x)
#define DUMPLN(x)
#define DEBUG(x)
#define DEBUGLN(x)
#define LINE()
#define LINELN()
#define CHECK(exp,act)
#define STOP(e)
#else
#define DUMP(x)  cerr << #x << " = " << (x)
#define DUMPLN(x)  DUMP(x) <<endl
#define DEBUG(x) DUMP(x) << LINE() << " " << __FILE__
#define DEBUGLN(x) DEBUG(x)<<endl
#define LINE()    cerr<< " (L" << __LINE__ << ")"
#define LINELN()    LINE()<<endl
#define CHECK(exp,act)  if(exp!=act){DUMPLN(exp);DEBUGLN(act);}
#define STOP(e)  CHECK(e,true);if(!(e)) exit(1);
#endif

template<class T> inline string toString(const vector<T>& x) {
	stringstream ss;
	REP(i,x.size()){
		if(i!=0)ss<<" ";
		ss<< x[i];
	}
	return ss.str();
}

template<class T> inline string toString(const vector<vector<T> >& map) {
	stringstream ss;
	REP(i,map.size()){
		if(i!=0)ss<<BR;
		ss<< toString(map[i]);
	}
	return ss.str();
}
template<class K,class V>  string toString(map<K,V>& x) {
	string res;stringstream ss;
	for(auto& p:x)ss<< p.first<<":" << p.second<<" ";
	return ss.str();
}

string BITtoString(int bit){
    stringstream ss;
    while(bit!=0){ss<<(bit%2);bit/=2;}
    string res=ss.str();reverse(ALL(res));
    return res;
}

template<typename T,typename V> inline T mod(T v,V MOD){
	return (v%MOD+MOD)%MOD;
}


class Main{
public:
	void run(){
	//	ifstream cin("in");
	//	ofstream cout( "out" );
		int D,N;cin >> D >> N;
		vector<int> ds(D);
		REP(i,D)cin >> ds[i];

		vector<int> as(N),bs(N),cs(N);
		REP(i,N)cin >> as[i] >> bs[i] >> cs[i];

		vector<vector<int> > dp(D,vector<int>(N,-1));
		REP(i,N){
			if(!IN(as[i],ds[0],bs[i]+1))continue;
			dp[0][i]=0;
		}
		for(int d=1;d<D;d++){
			REP(i,N){
				if(!IN(as[i],ds[d],bs[i]+1))continue;
				REP(j,N){
					if(dp[d-1][j]==-1)continue;
					dp[d][i]=max(dp[d][i],dp[d-1][j]+abs(cs[i]-cs[j]));				
				}
			}
		}
		int res=0;
		REP(i,N)res=max(res,dp[D-1][i]);

		cout << res <<endl;
	}
};
 int main(){
ios::sync_with_stdio(false);
 	Main().run();
 	return 0;
 }

C++: #include <iostream>
#include <string>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <utility>
#include <iomanip>

#define ll long long int
#define pb push_back
#define mk make_pair
#define pq priority_queue

using namespace std;
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
const int inf = 1e9;
const ll linf = 1LL << 50;

int d, n;
int t[201];
int a[201], b[201], c[201];
int dp[201][201];

int main(int argc, char const* argv[])
{
	cin >> d >> n;
	for(int i = 0; i < d; i++)cin >> t[i];
	for(int i = 0; i < n; i++)cin >> a[i] >> b[i] >> c[i];
	for(int i = 0; i < d - 1; i++){
			for(int j = 0; j < n; j++){
					if(a[j] > t[i] || b[j] < t[i])continue;
					for(int k = 0; k < n; k++){
							if(a[k] > t[i+1] || b[k] < t[i+1])continue;
							dp[i+1][k] = max(dp[i+1][k], dp[i][j] + abs(c[j] - c[k]));
					}
			}
	}
	int res = 0;
	for(int i = 0; i < n; i++){
			res = max(res, dp[d-1][i]);
	}
	cout << res << endl;
	return 0;
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define forever for (;;)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
template<typename A> using V = std::vector<A>;
template<typename A> using F = std::function<A>;
template<typename A, typename B> using P = std::pair<A, B>;
using pii = P<int, int>;
using vi = V<int>;
using vd = V<double>;
using vs = V<std::string>;
using vpii = V<pii>;
using vvi = V<vi>;
using vvpii = V<vpii>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
template<typename T> std::istream &operator>>(std::istream &is, std::vector<T> &v) { for (T &x : v) is >> x; return is; }
template<typename A, typename B> std::istream &operator>>(std::istream &is, std::pair<A, B> &p) { is >> p.first; is >> p.second; return is; }
using namespace std;
// clang-format on

main {
  int d, n;
  cin >> d >> n;
  vi t(d);
  cin >> t;
  vi a(n), b(n), c(n);
  rep(i, n) cin >> a[i] >> b[i] >> c[i];
  vvi dp(d, vi(n, -1));
  rep(i, n) if (a[i] <= t[0] && t[0] <= b[i]) dp[0][i] = 0;
  loop(i, 1, d) rep(j, n) rep(k, n) {
    if (t[i] < a[k] || b[k] < t[i] || dp[i - 1][j] == -1) continue;
    cmax(dp[i][k], dp[i - 1][j] + abs(c[k] - c[j]));
  }
  cout << *max_element(all(dp.back())) << endl;
}

C++: #include <bits/stdc++.h>

using namespace std;

typedef struct {
	int a;
	int b;
	int c;
} fuku_t;

int d, n;

int t[200];
fuku_t fuku[200];

int dp[200][200];

int main()
{
	cin >> d >> n;

	for (int i = 0; i < d; ++i) cin >> t[i];

	for (int i = 0; i < n; ++i) scanf("%d %d %d", &fuku[i].a, &fuku[i].b, &fuku[i].c);

	for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) {
		if (fuku[j].a <= t[0] && t[0] <= fuku[j].b && fuku[i].a <= t[1] && t[1] <= fuku[i].b) {
			dp[1][i] = max(dp[1][i], abs(fuku[j].c - fuku[i].c));
		}
	}

	for (int i = 2; i < d; ++i) for (int j = 0; j < n; ++j) for (int k = 0; k < n; ++k) {
		if (fuku[j].a <= t[i] && t[i] <= fuku[j].b && fuku[k].a <= t[i - 1] && t[i - 1] <= fuku[k].b) {
			dp[i][j] = max(dp[i][j], dp[i - 1][k] + abs(fuku[k].c - fuku[j].c));
		}
	}

	int ans = 0;

	for (int i = 0; i < n; ++i) ans = max(ans, dp[d - 1][i]);

	printf("%d\n", ans);
}