Find First and Last Position of Element

1package pkg5leetcode.top100;2 3/*4 * Find First and Last Position of Element | LC 345 * APPROACH: Two binary searches for leftmost and rightmost target.6 * COMPLEXITY: Time O(log n), Space O(1)7 */8public class top100_LC34FindFirstAndLastPositionOfElement {9    static int[] searchRange(int[] nums, int target) {10        return new int[]{leftBound(nums, target), rightBound(nums, target)};11    }12 13    static int leftBound(int[] a, int t) {14        int lo = 0, hi = a.length - 1, res = -1;15        while (lo <= hi) {16            int mid = lo + (hi - lo) / 2;17            if (a[mid] >= t) hi = mid - 1;18            else lo = mid + 1;19            if (a[mid] == t) res = mid;20        }21        return res;22    }23 24    static int rightBound(int[] a, int t) {25        int lo = 0, hi = a.length - 1, res = -1;26        while (lo <= hi) {27            int mid = lo + (hi - lo) / 2;28            if (a[mid] <= t) lo = mid + 1;29            else hi = mid - 1;30            if (a[mid] == t) res = mid;31        }32        return res;33    }34 35    public static void main(String[] args) {36        check(java.util.Arrays.equals(searchRange(new int[]{5, 7, 7, 8, 8, 10}, 8), new int[]{3, 4}), "case1");37        check(java.util.Arrays.equals(searchRange(new int[]{5, 7, 7, 8, 8, 10}, 6), new int[]{-1, -1}), "case2");38        System.out.println("all tests passed");39    }40 41    static void check(boolean cond, String name) {42        if (!cond) throw new AssertionError("FAILED: " + name);43        System.out.println("  PASS " + name);44    }45}