feat: add rust solution to lc problem: No.0050 (#1292)

Author: xzhseh

solution/0000-0099/0050.Pow(x, n)/README.md

@@ -124,6 +124,37 @@ public:
 };
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    #[allow(dead_code)]
+    pub fn my_pow(x: f64, n: i32) -> f64 {
+        let mut x = x;
+        let n = n as i64;
+        if n >= 0 {
+            Self::quick_pow(&mut x, n)
+        } else {
+            1.0 / Self::quick_pow(&mut x, -n)
+        }
+    }
+
+    #[allow(dead_code)]
+    fn quick_pow(x: &mut f64, mut n: i64) -> f64 {
+        // `n` should greater or equal to zero
+        let mut ret = 1.0;
+        while n != 0 {
+            if n & 0x1 == 1 {
+                ret *= *x;
+            }
+            *x *= *x;
+            n >>= 1;
+        }
+        ret
+    }
+}
+```
+
 ### **Go**
 
 ```go

solution/0000-0099/0050.Pow(x, n)/README_EN.md

@@ -108,6 +108,37 @@ public:
 };
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    #[allow(dead_code)]
+    pub fn my_pow(x: f64, n: i32) -> f64 {
+        let mut x = x;
+        let n = n as i64;
+        if n >= 0 {
+            Self::quick_pow(&mut x, n)
+        } else {
+            1.0 / Self::quick_pow(&mut x, -n)
+        }
+    }
+
+    #[allow(dead_code)]
+    fn quick_pow(x: &mut f64, mut n: i64) -> f64 {
+        // `n` should greater or equal to zero
+        let mut ret = 1.0;
+        while n != 0 {
+            if n & 0x1 == 1 {
+                ret *= *x;
+            }
+            *x *= *x;
+            n >>= 1;
+        }
+        ret
+    }
+}
+```
+
 ### **Go**
 
 ```go

solution/0000-0099/0050.Pow(x, n)/Solution.rs

@@ -0,0 +1,26 @@
+impl Solution {
+    #[allow(dead_code)]
+    pub fn my_pow(x: f64, n: i32) -> f64 {
+        let mut x = x;
+        let n = n as i64;
+        if n >= 0 {
+            Self::quick_pow(&mut x, n)
+        } else {
+            1.0 / Self::quick_pow(&mut x, -n)
+        }
+    }
+
+    #[allow(dead_code)]
+    fn quick_pow(x: &mut f64, mut n: i64) -> f64 {
+        // `n` should greater or equal to zero
+        let mut ret = 1.0;
+        while n != 0 {
+            if n & 0x1 == 1 {
+                ret *= *x;
+            }
+            *x *= *x;
+            n >>= 1;
+        }
+        ret
+    }
+}