Российские газопроводы

#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <vector>
#include <stdio.h>
#include <cmath>
#include <math.h>
#include <queue>
#include <stack>
#include <climits>
#include <deque>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long llu;

#define modulo pow(10,9)+7
#define eps pow(10,-9)
#define forn(i, n) for(int i = 0; i < n; ++i)
#define rforn(i, n) for (int i = n; i >= 0; --i)
#define files freopen("input.txt", "rt", stdin); freopen("output.txt", "wt", stdout)
#define speed ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define all(n) n.begin(), n.end()
#define rall(n) n.rbegin(), n.rend()

vector<pair<int, int>> graf[501];
int S[501];

void decs(int a)
{
    queue<int>next;
    next.push(a);
    S[a] = 0;
    while (next.size() != 0)
    {
        int now = next.front();
        next.pop();
        for (int i = 0; i < graf[now].size(); i++)
        {
            if (S[graf[now][i].first] < S[now] + graf[now][i].second)
            {
                S[graf[now][i].first] = S[now] + graf[now][i].second;
                next.push(graf[now][i].first);
            }
        }
    }
}
int main()
{
    int n, m, a, b;
    int prom, prom2, l;
    cin >> n >> m;
    for (int i = 1; i <= 500; i++)
    {
        S[i] = 0;
    }
    for (int i = 1; i <= m; i++)
    {
        cin >> prom >> prom2 >> l;
        graf[prom].push_back({ prom2,l });
    }
    cin >> a >> b;
    if (graf[a].size() != 0)
    {
        decs(a);
        if (S[b] == 0 && b != a)
        {
            cout << "No solution";
        }
        else
            cout << S[b];
    }
    else
        cout << "No solution";
    system("pause");
    return 0;
}