变换原来代码的思路对其再进行改写，但实现的功能不变

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
using namespace std;

typedef long long LL;
const int N = 105, M = 2505, L = 20;
const LL INF = 1e18;

int n, m, K, l;
LL d[N][N], w[N][N], g[L][N][N], f[N], t[N];

struct Edge {
int u, v, w;
};

int main() {
memset(g, 0x3f, sizeof g);

scanf("%d%d%d", &n, &m, &K);
l = log2(K);

for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (i != j) {
d[i][j] = INF;
}
}
}

for (int i = 1; i <= m; i++) {
scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);
d[e[i].u][e[i].v] = min(d[e[i].u][e[i].v], (LL)e[i].w);
}

for (int k = 1; k <= n; k++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
}
}
}

for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
w[i][j] = d[i][j];
for (int k = 1; k <= m; k++) {
w[i][j] = min(w[i][j], d[i][e[k].u] - e[k].w + d[e[k].v][j]);
}
g[0][i][j] = w[i][j];
}
}

for (int c = 1; c <= l; c++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
for (int k = 1; k <= n; k++) {
g[c][i][j] = min(g[c][i][j], g[c - 1][i][k] + g[c - 1][k][j]);
}
}
}
}

for (int i = 1; i <= n; i++) {
f[i] = d[1][i];
}

for (int c = 0; c <= l; c++) {
if (K >> c & 1) {
for (int i = 1; i <= n; i++) {
t[i] = f[i];
}
memset(f, 0x3f, sizeof f);
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
f[i] = min(f[i], t[j] + g[c][j][i]);
}
}
}
}

printf("%lld\n", f[n]);

return 0;
}