1 files changed, 42 insertions, 0 deletions
diff --git a/leetcode/3637/main.c b/leetcode/3637/main.c
new file mode 100644
index 0000000..6f5cf7d
--- /dev/null
+++ b/leetcode/3637/main.c
@@ -0,0 +1,42 @@
+#include <stdbool.h>
+bool isTrionic(int *nums, int numsSize) {
+  if (numsSize < 4) {
+    return false;
+  }
+
+  // 防止[9,4,6,8]
+  if (nums[0] > nums[1]) {
+    return false;
+  }
+
+  enum { UP1, DOWN, UP2 } state = UP1;
+
+  // 状态机真好玩嘻嘻嘻
+  for (int i = 0; i < numsSize - 1; i++) {
+    if (nums[i] == nums[i + 1]) {
+      return false;
+    }
+
+    if (state == UP1) {
+      if (nums[i] < nums[i + 1]) {
+        continue;
+      } else {
+        state = DOWN;
+      }
+    } else if (state == DOWN) {
+      if (nums[i] > nums[i + 1]) {
+        continue;
+      } else {
+        state = UP2;
+      }
+    } else { // 既不等于UP1, 也不等于DOWN，就等于UP2
+      if (nums[i] < nums[i + 1]) {
+        continue;
+      } else {
+        return false;
+      }
+    }
+  }
+
+  return state == UP2;
+}