793D Presents in Bankopolis

#include<iostream>
#include<vector>
#include<string>
#include<set>
#include<map>
#include<algorithm>
#include<queue>
#include<list>
#include<stack>
#include<cstdio>
#include<fstream>
#include<numeric>
#include<functional>
#include<utility>
#include<memory.h>
using namespace std;
using namespace placeholders;

int area[82][82];
int dp[82][82][82][82];
int n, k, m;

int Cal(int left, int right, int cur, int amount){
	if (dp[left][right][cur][amount] != -1) return dp[left][right][cur][amount];
	if (amount == 1){
		dp[left][right][cur][amount] = 0;
		return 0;
	}
	int res = 1e8;
	for (int i = 1; i <= n; i++){
		if (area[cur][i] <= 1000 && i>left&&i<right){
			int l = left, r = right;
			if (cur < i) l = cur;
			else r = cur;
			res = min(res, area[cur][i] + Cal(l, r, i, amount - 1));
		}
	}
	dp[left][right][cur][amount] = res;
	return res;
}

int main(){
	while (cin >> n >> k){
		cin >> m;
		for (int i = 1; i <= n; i++)
			for (int j = 1; j <= n; j++) area[i][j] = 1e8;
		memset(dp, -1, sizeof(dp));
		for (int i = 1; i <= m; i++){
			int u, v, c;
			cin >> u >> v >> c;
			area[u][v] = min(area[u][v], c);
		}
		int ans = 1e8;
		for (int i = 1; i <= n; i++){
			int left = 0;
			int right = n + 1;
			ans = min(ans, Cal(left, right, i, k));
		}
		if (ans >= 1e8) cout << "-1" << endl;
		else cout << ans << endl;
	}
	return 0;
}