diff --git a/TangDou/Topic/PrefixAndSuffix/P3406.cpp b/TangDou/Topic/PrefixAndSuffix/P3406.cpp
new file mode 100644
index 0000000..4376f2e
--- /dev/null
+++ b/TangDou/Topic/PrefixAndSuffix/P3406.cpp
@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define int long long
+#define endl "\n"
+
+signed main() {
+    int n, m, ans = 0;
+    scanf("%lld%lld", &n, &m);
+    int p[m + 1];                           // 用于记录经过站点的顺序
+    int t[n + 1] = {};                      // 用于记录站点之间的路径经过的次数
+    int a[n + 1], b[n + 1], c[n + 1], x, y; // 用于记录每段路径所花的费用
+    for (int i = 1; i <= m; i++)
+        scanf("%lld", &p[i]);
+    for (int i = 1; i <= n - 1; i++)
+        scanf("%lld%lld%lld", &a[i], &b[i], &c[i]);
+    for (int i = 1; i <= m - 1; i++) { // 所有的区间都以较小的点排在前面，例如：2-1，5-3都用1-2，3-5表示，且每一段都用前面较小的点作为标记！！！！
+        if (p[i] > p[i + 1]) {
+            x = p[i + 1];
+            y = p[i];
+        } else {
+            x = p[i];
+            y = p[i + 1];
+        }
+        t[x]++;
+        t[y]--;
+    }
+    for (int i = 1; i <= n; i++) { // 求前缀和
+        t[i] += t[i - 1];
+    }
+    for (int i = 1; i <= n - 1; i++)
+        ans += min(a[i] * t[i], (b[i] * t[i] + c[i])); // 求总的最小就是把每一段的最小相加
+    printf("%lld", ans);
+}
\ No newline at end of file