create dev channel

zeta/py/completed/1865.py

@@ -0,0 +1,35 @@
+import sys
+
+input = sys.stdin.readline
+
+INF = 1 << 30
+
+
+def bellman_ford(N, E, start=1):
+    dist = [INF] * (N + 1)
+    parent = [0] * (N + 1)
+
+    dist[start] = 0
+    for _ in range(1, N + 1):
+        for u, v, w in E:
+            if dist[u] + w < dist[v]:
+                dist[v] = dist[u] + w
+                parent[v] = u
+
+    for u, v, w in E:
+        if dist[u] + w < dist[v]:
+            return -INF
+    return dist[N]
+
+
+if __name__ == "__main__":
+    T = int(input())
+    for _ in range(T):
+        N, M, W = map(int, input().split())
+        E = []
+        for s, e, w in [map(int, input().split()) for _ in range(M)]:
+            E.append((s, e, w))
+            E.append((e, s, w))
+        for s, e, w in [map(int, input().split()) for _ in range(W)]:
+            E.append((s, e, -w))
+        print("YES" if bellman_ford(N, E) < 0 else "NO")