finish reordered power of 2

18-50/reordered-power-of-2/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "reordered-power-of-2"
+version = "0.1.0"
+authors = ["Checky-Hu <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

18-50/reordered-power-of-2/src/main.rs

@@ -0,0 +1,67 @@
+use std::env;
+use std::str::FromStr;
+
+struct Solution {}
+
+impl Solution {
+    fn helper(
+        bytes: &[u8],
+        index: usize,
+        len: usize,
+        flags: &mut Vec<bool>,
+        result: &mut String,
+    ) -> bool {
+        if index == len {
+            let mut t: i32 = i32::from_str(result).unwrap_or(0);
+            while t != 1 {
+                if t & 1 == 0 {
+                    t >>= 1;
+                } else {
+                    return false;
+                }
+            }
+            true
+        } else {
+            for i in 0..len {
+                if flags[i] || (index == 0 && bytes[i] == b'0') {
+                    continue;
+                }
+                flags[i] = true;
+                result.push(bytes[i] as char);
+                if Solution::helper(bytes, index + 1, len, flags, result) {
+                    return true;
+                }
+                result.pop();
+                flags[i] = false;
+            }
+            false
+        }
+    }
+
+    pub fn reordered_power_of2(n: i32) -> bool {
+        let s: String = n.to_string();
+        let len: usize = s.len();
+        let mut flags: Vec<bool> = vec![false; len];
+        let mut result: String = String::new();
+        Solution::helper(s.as_bytes(), 0, len, &mut flags, &mut result)
+    }
+}
+
+fn main() {
+    let mut ret: i32 = 0;
+    for (index, arg) in env::args().enumerate() {
+        if 1 == index {
+            ret += 1;
+            let n: i32 = i32::from_str(&arg).expect("Error parse.");
+            println!(
+                "Power of 2 after reorder: {}",
+                Solution::reordered_power_of2(n)
+            );
+            break;
+        }
+    }
+
+    if 0 == ret {
+        println!("Require at least one parameter.");
+    }
+}