|
| 1 | +--- |
| 2 | +comments: true |
| 3 | +difficulty: Medium |
| 4 | +edit_url: antim |
| 5 | +rating: 1382 |
| 6 | +source: Weekly Contest 171 Q2 |
| 7 | +tags: |
| 8 | + - Bit Manipulation |
| 9 | +--- |
| 10 | + |
| 11 | +<!-- problem:start --> |
| 12 | + |
| 13 | +# [1318. Minimum Flips to Make a OR b Equal to c](https://leetcode.com/problems/minimum-flips-to-make-a-or-b-equal-to-c) |
| 14 | + |
| 15 | + |
| 16 | +## Description |
| 17 | + |
| 18 | +<!-- description:start --> |
| 19 | + |
| 20 | +<p>Given 3 positives numbers <code>a</code>, <code>b</code> and <code>c</code>. Return the minimum flips required in some bits of <code>a</code> and <code>b</code> to make ( <code>a</code> OR <code>b</code> == <code>c</code> ). (bitwise OR operation).<br /> |
| 21 | +Flip operation consists of change <strong>any</strong> single bit 1 to 0 or change the bit 0 to 1 in their binary representation.</p> |
| 22 | + |
| 23 | +<p> </p> |
| 24 | +<p><strong class="example">Example 1:</strong></p> |
| 25 | + |
| 26 | +<p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1300-1399/1318.Minimum%20Flips%20to%20Make%20a%20OR%20b%20Equal%20to%20c/images/sample_3_1676.png" style="width: 260px; height: 87px;" /></p> |
| 27 | + |
| 28 | +<pre> |
| 29 | +<strong>Input:</strong> a = 2, b = 6, c = 5 |
| 30 | +<strong>Output:</strong> 3 |
| 31 | +<strong>Explanation: </strong>After flips a = 1 , b = 4 , c = 5 such that (<code>a</code> OR <code>b</code> == <code>c</code>)</pre> |
| 32 | + |
| 33 | +<p><strong class="example">Example 2:</strong></p> |
| 34 | + |
| 35 | +<pre> |
| 36 | +<strong>Input:</strong> a = 4, b = 2, c = 7 |
| 37 | +<strong>Output:</strong> 1 |
| 38 | +</pre> |
| 39 | + |
| 40 | +<p><strong class="example">Example 3:</strong></p> |
| 41 | + |
| 42 | +<pre> |
| 43 | +<strong>Input:</strong> a = 1, b = 2, c = 3 |
| 44 | +<strong>Output:</strong> 0 |
| 45 | +</pre> |
| 46 | + |
| 47 | +<p> </p> |
| 48 | +<p><strong>Constraints:</strong></p> |
| 49 | + |
| 50 | +<ul> |
| 51 | + <li><code>1 <= a <= 10^9</code></li> |
| 52 | + <li><code>1 <= b <= 10^9</code></li> |
| 53 | + <li><code>1 <= c <= 10^9</code></li> |
| 54 | +</ul> |
| 55 | + |
| 56 | +<!-- description:end --> |
| 57 | + |
| 58 | +## Solutions |
| 59 | + |
| 60 | +<!-- solution:start --> |
| 61 | + |
| 62 | +### Solution 1: Bit Manipulation |
| 63 | + |
| 64 | +We can enumerate each bit of the binary representation of $a$, $b$, and $c$, denoted as $x$, $y$, and $z$ respectively. If the bitwise OR operation result of $x$ and $y$ is different from $z$, we then check if both $x$ and $y$ are $1$. If so, we need to flip twice, otherwise, we only need to flip once. We accumulate all the required flip times. |
| 65 | + |
| 66 | +The time complexity is $O(\log M)$, where $M$ is the maximum value of the numbers in the problem. The space complexity is $O(1)$. |
| 67 | + |
| 68 | +<!-- tabs:start --> |
| 69 | + |
| 70 | +#### Python3 |
| 71 | + |
| 72 | +```python |
| 73 | +class Solution: |
| 74 | + def minFlips(self, a: int, b: int, c: int) -> int: |
| 75 | + ans = 0 |
| 76 | + for i in range(32): |
| 77 | + x, y, z = a >> i & 1, b >> i & 1, c >> i & 1 |
| 78 | + ans += x + y if z == 0 else int(x == 0 and y == 0) |
| 79 | + return ans |
| 80 | +``` |
| 81 | + |
| 82 | +#### Java |
| 83 | + |
| 84 | +```java |
| 85 | +class Solution { |
| 86 | + public int minFlips(int a, int b, int c) { |
| 87 | + int ans = 0; |
| 88 | + for (int i = 0; i < 32; ++i) { |
| 89 | + int x = a >> i & 1, y = b >> i & 1, z = c >> i & 1; |
| 90 | + ans += z == 0 ? x + y : (x == 0 && y == 0 ? 1 : 0); |
| 91 | + } |
| 92 | + return ans; |
| 93 | + } |
| 94 | +} |
| 95 | +``` |
| 96 | + |
| 97 | +#### C++ |
| 98 | + |
| 99 | +```cpp |
| 100 | +class Solution { |
| 101 | +public: |
| 102 | + int minFlips(int a, int b, int c) { |
| 103 | + int ans = 0; |
| 104 | + for (int i = 0; i < 32; ++i) { |
| 105 | + int x = a >> i & 1, y = b >> i & 1, z = c >> i & 1; |
| 106 | + ans += z == 0 ? x + y : (x == 0 && y == 0 ? 1 : 0); |
| 107 | + } |
| 108 | + return ans; |
| 109 | + } |
| 110 | +}; |
| 111 | +``` |
| 112 | +
|
| 113 | +<!-- tabs:end --> |
| 114 | +
|
| 115 | +<!-- solution:end --> |
| 116 | +
|
| 117 | +<!-- problem:end --> |
0 commit comments