墨染空大佬永远的神, 不过这个看起来更清晰, 能比大佬的代码更加易懂

#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <cmath>

using namespace std;

const int NUMBER = 210, EDGE_NUMBER = NUMBER * 2;

int k, edge_number, start_node, end_node;
int dist[NUMBER][NUMBER][20];
struct Edge {
    int ver1, ver2, val;
} arr[EDGE_NUMBER];
vector<int> nums;
int len;

int get(int val) {
    return lower_bound(nums.begin(), nums.end(), val) - nums.begin();
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> k >> edge_number >> start_node >> end_node;
//  计算k有多少位
    len = log2(k);

    for (int i = 0; i < edge_number; ++i) {
        int ver1, ver2, val;
        cin >> val >> ver1 >> ver2;
        arr[i] = {ver1, ver2, val};
        nums.push_back(ver1);
        nums.push_back(ver2);
    }

    sort(nums.begin(), nums.end());
    nums.erase(unique(nums.begin(), nums.end()), nums.end());

    start_node = get(start_node), end_node = get(end_node);
    memset(dist, 0x3f, sizeof dist);

    for (int i = 0; i < edge_number; ++i) {
        arr[i].ver1 = get(arr[i].ver1);
        arr[i].ver2 = get(arr[i].ver2);

//      初始化点与点之间的初始距离
        int ver1 = arr[i].ver1, ver2 = arr[i].ver2;
        dist[ver1][ver2][0] = dist[ver2][ver1][0] = min(dist[ver1][ver2][0], arr[i].val);
    }

    for (int l = 1; l <= len; ++l) {
        for (int i = 0; i < nums.size(); ++i) {
            for (int j = 0; j < nums.size(); ++j) {
                for (int z = 0; z < nums.size(); ++z) {
                    dist[i][j][l] = min(dist[i][j][l], dist[i][z][l - 1] + dist[z][j][l - 1]);
                }
            }
        }
    }

    int to_curr[NUMBER], start_to[NUMBER];
    memset(start_to, 0x3f, sizeof start_to);
    start_to[start_node] = 0;

    for (int l = 0; l <= len; ++l) {
        if (k >> l & 1) {
            memset(to_curr, 0x3f, sizeof to_curr);

            for (int i = 0; i < nums.size(); ++i) {
                for (int j = 0; j < nums.size(); ++j) {
                    to_curr[i] = min(to_curr[i], start_to[j] + dist[j][i][l]);
                }
            }
            memcpy(start_to, to_curr, sizeof to_curr);
        }
    }

    cout << to_curr[end_node] << endl;

    return 0;
}