76 lines
2.2 KiB
Rust
76 lines
2.2 KiB
Rust
#[cfg(test)]
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mod tests {
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use super::binary_search;
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#[test]
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fn binary_search_primegen_test() {
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let haystack = [1, 3, 4, 69, 71, 81, 90, 99, 420, 1337, 69420];
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assert_eq!(binary_search(&haystack, 69), Some((true, 3)));
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assert_eq!(binary_search(&haystack, 1336), Some((false, 0)));
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assert_eq!(binary_search(&haystack, 69420), Some((true, 10)));
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assert_eq!(binary_search(&haystack, 69421), Some((false, 0)));
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assert_eq!(binary_search(&haystack, 1), Some((true, 0)));
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assert_eq!(binary_search(&haystack, 0), Some((false, 0)));
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}
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#[test]
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fn test_binary_search_found() {
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let haystack = [1, 3, 5, 7, 9];
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assert_eq!(binary_search(&haystack, 5), Some((true, 2)));
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}
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#[test]
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fn test_binary_search_not_found() {
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let haystack = [1, 3, 5, 7, 9];
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assert_eq!(binary_search(&haystack, 4), Some((false, 0)));
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}
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#[test]
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fn test_binary_search_empty() {
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let haystack: [usize; 0] = [];
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assert_eq!(binary_search(&haystack, 4), Some((false, 0)));
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}
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#[test]
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fn test_binary_search_single_element_found() {
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let haystack = [5];
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assert_eq!(binary_search(&haystack, 5), Some((true, 0)));
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}
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#[test]
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fn test_binary_search_single_element_not_found() {
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let haystack = [5];
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assert_eq!(binary_search(&haystack, 3), Some((false, 0)));
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}
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#[test]
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fn test_binary_search_multiple_elements_not_found() {
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let haystack = [1, 2, 3, 4, 5];
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assert_eq!(binary_search(&haystack, 6), Some((false, 0)));
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}
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#[test]
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fn test_binary_search_multiple_elements_found() {
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let haystack = [1, 2, 3, 4, 5];
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assert_eq!(binary_search(&haystack, 3), Some((true, 2)));
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}
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}
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pub fn binary_search(haystack: &[usize], needle: usize) -> Option<(bool, usize)> {
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let mut low = 0;
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let mut high = haystack.len();
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while low < high {
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let midpoint = low + (high - low) / 2;
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let value = haystack[midpoint];
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if value == needle {
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return Some((true, midpoint));
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} else if value > needle {
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high = midpoint;
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} else {
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low = midpoint + 1;
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}
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}
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Some((false, 0)) // Return 0 as index if value is not found
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}
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