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OI-codes/S2OJ/106/data/std.cpp

79 lines
1.6 KiB (Stored with Git LFS)
C++

#include <bits/stdc++.h>
#define R register int
#define ll long long
#define db double
#define FOR(i, j, k) for (R i = j; i <= k; i++)
#define DEC(i, j, k) for (R i = j; i >= k; i--)
#define walk(i, u) for (R i = 0; i < g[u].size(); i++)
#define visch(i, u) for (R i = head[u]; i; i = edge[i].next)
using namespace std;
inline int read() {
int x = 0;
bool flag = 0;
int ch = getchar();
while ('0' > ch || ch > '9') {
if (ch == '-')
flag = 1;
ch = getchar();
}
while ('0' <= ch && ch <= '9') {
x = (x << 1) + (x << 3) + (ch ^ 48);
ch = getchar();
}
return flag ? -x : x;
}
const int maxn = 2510, maxm = 6210;
int n, m, s, t;
struct E {
int to, nxt, w;
} edge[maxm << 1];
int head[maxn], ec;
inline void adde(int u, int v, int w) {
edge[++ec].to = v;
edge[ec].nxt = head[u];
edge[ec].w = w;
head[u] = ec;
}
deque<int> q;
ll dis[maxn];
bool vis[maxn];
inline void spfa() {
FOR(i, 1, n)
dis[i] = 0x3f3f3f3f3f3f3f3f;
dis[s] = 0;
vis[s] = 1;
q.push_back(s);
while (q.size()) {
int u = q.front();
q.pop_front();
vis[u] = 0;
for (int i = head[u]; i; i = edge[i].nxt) {
int v = edge[i].to;
if (dis[u] + edge[i].w < dis[v]) {
dis[v] = dis[u] + edge[i].w;
if (!vis[v])
q.push_back(v);
}
}
}
}
int main() {
n = read(), m = read(), s = read(), t = read();
FOR(i, 1, m) {
int x = read(), y = read(), z = read();
adde(x, y, z);
adde(y, x, z);
}
spfa();
printf("%lld", dis[t]);
return 0;
}