19 lines
652 B
Rust
19 lines
652 B
Rust
pub fn missing_number(numbers: Vec<i32>) -> i32 {
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// The range of numbers can be described as the total sum of all possible
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// numbers in that range.
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let total_range = (0..=numbers.len() as i32).sum::<i32>();
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// And since only one number is missing from that range, the difference
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// between the range's sum and the numbers' sum will be that missing number.
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let sum_of_numbers = numbers.iter().sum::<i32>();
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total_range - sum_of_numbers
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}
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#[test]
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fn test_missing_number() {
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assert_eq!(missing_number(vec![3, 0, 1]), 2);
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assert_eq!(missing_number(vec![0, 1]), 2);
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assert_eq!(missing_number(vec![9, 6, 4, 2, 3, 5, 7, 0, 1]), 8);
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}
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