405 Convert a Number to Hexadecimal

Author: Kilerd

src/convert_a_number_to_hexadecimal.rs

@@ -0,0 +1,114 @@
+use std::ops::{Shl, ShlAssign, Shr};
+use std::hint::unreachable_unchecked;
+
+/// @number 405
+/// @title Convert a Number to Hexadecimal
+/// @url https://leetcode.com/problems/convert-a-number-to-hexadecimal
+/// @difficulty easy
+
+//
+//Given an integer, write an algorithm to convert it to hexadecimal. For negativ
+//e integer, two’s complement method is used.
+// 
+//
+// Note:
+// 
+// All letters in hexadecimal (a-f) must be in lowercase. 
+// The hexadecimal string must not contain extra leading 0s. If the number is ze
+//ro, it is represented by a single zero character '0'; otherwise, the first chara
+//cter in the hexadecimal string will not be the zero character. 
+// The given number is guaranteed to fit within the range of a 32-bit signed int
+//eger. 
+// You must not use any method provided by the library which converts/formats th
+//e number to hex directly. 
+// 
+// 
+//
+// Example 1:
+// 
+//Input:
+//26
+//
+//Output:
+//"1a"
+// 
+// 
+//
+// Example 2:
+// 
+//Input:
+//-1
+//
+//Output:
+//"ffffffff"
+// 
+// Related Topics Bit Manipulation 
+// 👍 433 👎 112
+
+struct Solution;
+
+//leetcode submit region begin(Prohibit modification and deletion)
+impl Solution {
+    pub fn to_hex(num: i32) -> String {
+        if num == 0 { return "0".into(); }
+
+
+        let mut leading_zero = false;
+        let mut ret = String::new();
+        let mask: u32 = 0xf0000000;
+
+        let mut looping_num: u32 = num as u32;
+        for i in 0..8 {
+            let i1 = (looping_num & mask) >> 28;
+            let position_char = match i1 {
+                0 => '0',
+                1 => '1',
+                2 => '2',
+                3 => '3',
+                4 => '4',
+                5 => '5',
+                6 => '6',
+                7 => '7',
+                8 => '8',
+                9 => '9',
+                10 => 'a',
+                11 => 'b',
+                12 => 'c',
+                13 => 'd',
+                14 => 'e',
+                15 => 'f',
+                _ => unreachable!()
+            };
+
+            if position_char != '0' || leading_zero == true {
+                ret.push(position_char);
+                leading_zero = true;
+            }
+
+            looping_num <<= 4;
+        }
+        ret
+    }
+}
+//leetcode submit region end(Prohibit modification and deletion)
+
+
+#[cfg(test)]
+mod test {
+    use crate::convert_a_number_to_hexadecimal::Solution;
+
+    #[test]
+    fn test1() {
+        assert_eq!("1a".to_string(), Solution::to_hex(26));
+    }
+
+    #[test]
+    fn test2() {
+        assert_eq!("0", Solution::to_hex(0));
+    }
+
+    #[test]
+    fn test3() {
+        assert_eq!("ffffffff", Solution::to_hex(-1))
+    }
+}

src/main.rs

@@ -1,3 +1,4 @@
+mod convert_a_number_to_hexadecimal;
 mod permutations;
 mod add_two_number;
 mod array_partition_i;