```cpp
#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, m, tot, head[100005], ans[100005], flag[100005], sum[100005];
queue <int> q;
struct jc{
int to, val, net;
}e[100005];
void add(int x, int y, int z) {
e[++tot].to = y;
e[tot].val = z;
e[tot].net = head[x];
head[x] = tot;
}
bool spfa(int s) {
memset(flag, 0, sizeof(flag));
memset(ans, 0x7F, sizeof(ans));
ans[s] = 0;
sum[s] = 1;
flag[s] = 1;
q.push(s);
while(!q.empty()) {
int x = q.front();
q.pop();
flag[x] = 0;
for (int i = head[x]; i; i = e[i].net) {
int y = e[i].to;
if (ans[y] > ans[x] + e[i].val) {
ans[y] = ans[x] + e[i].val;
if(!flag[y]) {
q.push(y);
flag[y] = 1;
sum[y]++;
if (sum[y] > n + 1) return 0;
}
}
}
}
return 1;
}
signed main() {
cin >> n >> m;
for (int i = 1; i <= n; i++) add(0, i, 0);
for (int i = 1; i <= m; i++) {
int op, x, y, z;
cin >> op >> x >> y;
if (op == 1) {
cin >> z;
add(x, y, -z);
}
if (op == 2) {
cin >> z;
add(y, x, z);
}
else {
add(x, y, 0);
add(y, x, 0);
}
}
if (spfa(0)) cout << "Yes" << '\n';
else cout << "No" << '\n';
return 0;
}
```
by kaceqwq @ 2023-01-29 10:07:34
@[kaceqwq](/user/527992) `if (op == 2)` -> `else if (op == 2)`
by AZN_0975 @ 2023-01-29 10:21:23
@[AZN_0975](/user/476985) 感谢，我是sb
by kaceqwq @ 2023-01-29 10:22:53
@[kaceqwq](/user/527992)
```cpp
#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, m, tot, head[100005], ans[100005], flag[100005], sum[100005];
queue <int> q;
struct jc{
int to, val, net;
}e[100005];
void add(int x, int y, int z) {
e[++tot].to = y;
e[tot].val = z;
e[tot].net = head[x];
head[x] = tot;
}
bool spfa(int s) {
memset(flag, 0, sizeof(flag));
memset(ans, 0x3F, sizeof(ans));
ans[s] = 0;
flag[s] = 1;
q.push(s);
while(!q.empty()) {
int x = q.front();
q.pop();
flag[x] = 0;
for (int i = head[x]; i; i = e[i].net) {
int y = e[i].to;
if (ans[y] > ans[x] + e[i].val) {
ans[y] = ans[x] + e[i].val;
sum[y]++;
if (sum[y] > n) return 0;
if(!flag[y]) {
q.push(y);
flag[y] = 1;
}
}
}
}
return 1;
}
signed main() {
cin >> n >> m;
for (int i = 1; i <= n; i++) add(0, i, 0);
for (int i = 1; i <= m; i++) {
int op, x, y, z;
cin >> op >> x >> y;
if (op == 1) {
cin >> z;
add(x, y, -z);
}
else if (op == 2) {
cin >> z;
add(y, x, z);
}
else {
add(x, y, 0);
add(y, x, 0);
}
}
if (spfa(0)) cout << "Yes" << '\n';
else cout << "No" << '\n';
return 0;
}
```
by Texas_the_Omertosa @ 2023-01-29 10:25:12