From 2f1fe8ed723af972a10e208ea3c798dfba48b4d7 Mon Sep 17 00:00:00 2001
From: Mistivia <i@mistivia.com>
Date: Sat, 6 Sep 2025 22:54:30 +0800
Subject: solve 69

---
 c/0069/main.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 c/0069/main.c

diff --git a/c/0069/main.c b/c/0069/main.c
new file mode 100644
index 0000000..86aab4a
--- /dev/null
+++ b/c/0069/main.c
@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int mySqrt(int x) {
+    int64_t t = x;
+    int64_t ln = 0, rn = x;
+    while (ln <= rn) {
+        int64_t mid = ln + (rn - ln) / 2;
+        if (mid * mid < x) {
+            if ((mid + 1) * (mid + 1) > x) {
+                return mid;
+            }
+            ln = mid + 1;
+        } else if (mid * mid > x) {
+            rn = mid - 1;
+        } else {
+            return mid;
+        }
+    }
+    return -1;
+}
+
+int main() {
+    printf("%d\n", mySqrt(9));
+    return 0;
+}
-- 
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