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循环有序数组的二分查找
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| /** | |
| * @synopsis 二分法搜索循环有序数组 | |
| * | |
| * @param s 要查找的数组 | |
| * @param k 要查找的关键字 | |
| * | |
| * @returns 当 k 存在时返回 k 的下标，当 k 不存在时返回 -1 | |
| */ | |
| var foo = function (s, k) { | |
| var mid; | |
| var l = 0; | |
| var r = s.length - 1; | |
| while (l <= r) { | |
| mid = parseInt((l + r) / 2); | |
| if (k == s[mid]) { | |
| return mid; | |
| } else if (k < s[mid]) { | |
| if (s[l] < s[mid] && k >= s[l]) { | |
| r = mid - 1; | |
| } else { | |
| l = mid + 1; | |
| } | |
| } else if (k > s[mid]) { | |
| if (s[r] > s[mid] && k <= s[r]) { | |
| l = mid + 1; | |
| } else { | |
| r = mid - 1; | |
| } | |
| } | |
| } | |
| return -1; | |
| }; | |
| for (var i = -1; i <= 10; i++) { | |
| console.log(foo([5, 6, 7, 8, 9, 0, 1, 2, 3, 4], i)); | |
| // 输出 -1 5 6 7 8 9 0 1 2 3 4 -1 | |
| } |
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