From 5233639a89eede7b1b0229c7d155f03e436bee32 Mon Sep 17 00:00:00 2001
From: Frederick Chen <seventeen@ohdragonboi.cn>
Date: Fri, 14 Feb 2025 02:48:38 +0000
Subject: [PATCH] New: total 2 codes

---
 FZOI/【模板】负环.cpp | 63 +++++++++++++++++++++++++++++++++++++++++++
 FZOI/最短路径问题.cpp | 55 +++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)
 create mode 100644 FZOI/【模板】负环.cpp
 create mode 100644 FZOI/最短路径问题.cpp

diff --git a/FZOI/【模板】负环.cpp b/FZOI/【模板】负环.cpp
new file mode 100644
index 0000000..a1545c9
--- /dev/null
+++ b/FZOI/【模板】负环.cpp
@@ -0,0 +1,63 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF 0x3f3f3f3f3f3f3f3fl
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const lo N = 1e5 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+struct Edge {
+	lo u, v, w;
+};
+
+lo t, n, m;
+lo c, p, W;
+	
+vector<Edge> edge;
+
+lo dis[N], u, v, w;
+
+bool bellmanford(lo n, lo s)
+{
+	memset(dis, 0x3f, (n + 1) * sizeof(lo));
+	dis[s] = 0;
+	bool flag = false;
+	for (lo i = 1; i <= n; i++) {
+		flag = false;
+		for (lo j = 0; j < edge.size(); j++) {
+			u = edge[j].u, v = edge[j].v, w = edge[j].w;
+			if (dis[u] == INF) continue;
+			if (dis[v] > dis[u] + w) {
+				dis[v] = dis[u] + w;
+				flag = true;
+			}
+		}
+		if (!flag) {
+			break;
+		}
+	}
+	return flag;
+}
+
+signed main()
+{
+	cin >> t;
+	while (t--) {
+		edge.clear();
+		cin >> n >> m;
+		for (lo i = 1; i <= m; i++) {
+			cin >> c >> p >> W;
+			edge.push_back({c, p, W});
+			if (W >= 0) edge.push_back({p, c, W});
+		}
+		if (bellmanford(n, 1)) {
+			cout << "YES" << endl;
+		} else {
+			cout << "NO" << endl;
+		}
+	}
+}
diff --git a/FZOI/最短路径问题.cpp b/FZOI/最短路径问题.cpp
new file mode 100644
index 0000000..ebfe194
--- /dev/null
+++ b/FZOI/最短路径问题.cpp
@@ -0,0 +1,55 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+int n, m, s, t;
+double ma[101][101], dp[101][101];
+
+struct Node {
+    int x, y;
+} a[101];
+
+signed main()
+{
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cout.tie(0);
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i].x >> a[i].y;
+    }
+    cin >> m;
+    for (int i = 1; i <= m; i++) {
+        int c, d;
+        cin >> c >> d;
+        double k = sqrt(double(pow((a[c].x - a[d].x), 2)) + double(pow((a[c].y - a[d].y), 2)));
+        ma[c][d] = k;
+        ma[d][c] = k;
+    }
+    cin >> s >> t;
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= n; j++) {
+            if (ma[i][j]) {
+                dp[i][j] = ma[i][j];
+            } else {
+                dp[i][j] = INT_MAX;
+            }
+        }
+    }
+    for (int k = 1; k <= n; k++) {
+        for (int i = 1; i <= n; i++) {
+            for (int j = 1; j <= n; j++) {
+                dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j]);
+            }
+        }
+    }
+    printf("%.2lf", dp[s][t]);
+}