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Return -1 if target is not in array (#9)

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* return -1 if target is not in array

* return -1 if target is not in array (python)

* <= in binary search while loop
pull/14/head
Austin Green 7 years ago committed by Yangshun Tay
parent ae70816718
commit 4fa28c04ee
2 changed files with 14 additions and 14 deletions
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14
utilities/javascript/binarySearch.js
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@ -1,7 +1,7 @@
function binarySearch(arr, target) { function binarySearch(arr, target) {
let left = 0; let left = 0;
let right = arr.length - 1; let right = arr.length - 1;
while (left < right) { while (left <= right) {
let mid = left + Math.floor((right - left) / 2); let mid = left + Math.floor((right - left) / 2);
if (arr[mid] === target) { if (arr[mid] === target) {
return mid; return mid;
@ -12,15 +12,15 @@ function binarySearch(arr, target) {
right = mid - 1; right = mid - 1;
} }
} }
return left; return -1;
} }
console.log(binarySearch([1, 2, 3, 10], 1) === 0) console.log(binarySearch([1, 2, 3, 10], 1) === 0)
console.log(binarySearch([1, 2, 3, 10], 2) === 1) console.log(binarySearch([1, 2, 3, 10], 2) === 1)
console.log(binarySearch([1, 2, 3, 10], 3) === 2) console.log(binarySearch([1, 2, 3, 10], 3) === 2)
console.log(binarySearch([1, 2, 3, 10], 10) === 3) console.log(binarySearch([1, 2, 3, 10], 10) === 3)
console.log(binarySearch([1, 2, 3, 10], 9) === 3) console.log(binarySearch([1, 2, 3, 10], 9) === -1)
console.log(binarySearch([1, 2, 3, 10], 4) === 3) console.log(binarySearch([1, 2, 3, 10], 4) === -1)
console.log(binarySearch([1, 2, 3, 10], 0) === 0) console.log(binarySearch([1, 2, 3, 10], 0) === -1)
console.log(binarySearch([1, 2, 3, 10], 11) === 3) console.log(binarySearch([1, 2, 3, 10], 11) === -1)
console.log(binarySearch([5, 7, 8, 10], 3) === 0) console.log(binarySearch([5, 7, 8, 10], 3) === -1)

14
utilities/python/binary_search.py
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@ -1,7 +1,7 @@
def binary_search(arr, target): def binary_search(arr, target):
left = 0; left = 0;
right = len(arr) - 1 right = len(arr) - 1
while left < right: while left <= right:
mid = left + (right - left) // 2; mid = left + (right - left) // 2;
if arr[mid] == target: if arr[mid] == target:
return mid return mid
@ -9,14 +9,14 @@ def binary_search(arr, target):
left = mid + 1 left = mid + 1
else: else:
right = mid - 1 right = mid - 1
return left return -1
print(binary_search([1, 2, 3, 10], 1) == 0) print(binary_search([1, 2, 3, 10], 1) == 0)
print(binary_search([1, 2, 3, 10], 2) == 1) print(binary_search([1, 2, 3, 10], 2) == 1)
print(binary_search([1, 2, 3, 10], 3) == 2) print(binary_search([1, 2, 3, 10], 3) == 2)
print(binary_search([1, 2, 3, 10], 10) == 3) print(binary_search([1, 2, 3, 10], 10) == 3)
print(binary_search([1, 2, 3, 10], 9) == 3) print(binary_search([1, 2, 3, 10], 9) == -1)
print(binary_search([1, 2, 3, 10], 4) == 3) print(binary_search([1, 2, 3, 10], 4) == -1)
print(binary_search([1, 2, 3, 10], 0) == 0) print(binary_search([1, 2, 3, 10], 0) == -1)
print(binary_search([1, 2, 3, 10], 11) == 3) print(binary_search([1, 2, 3, 10], 11) == -1)
print(binary_search([5, 7, 8, 10], 3) == 0) print(binary_search([5, 7, 8, 10], 3) == -1)

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