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122 lines
4.2 KiB
122 lines
4.2 KiB
/**
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* @author shixuesen
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* @date 2023/6/18
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*/
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public class Solution0034 {
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public int[] searchRange(int[] nums, int target) {
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// 二分法查找，但是尝试用两个数绑定作为一个元素
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if (nums.length == 0) {
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return new int[]{-1, -1};
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}
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if (nums.length == 1 && nums[0] == target) {
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return new int[]{0, 0};
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}
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int left = 0, right = nums.length - 1;
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int leftIndex = -1, rightIndex = -1;
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while (left <= right) {
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int mid = left + (right - left) / 2;
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if (nums[mid] == target) {
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int subLeftIndex = - 1;
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int subRightIndex = -1;
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if (left <= mid - 1) {
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subLeftIndex = findLeftIndex(nums, target, left, mid - 1);
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}
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if (mid + 1 <= right) {
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subRightIndex = findRightIndex(nums, target, mid + 1, right);
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}
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if (subLeftIndex > -1 && subLeftIndex < mid) {
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leftIndex = subLeftIndex;
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} else {
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leftIndex = mid;
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}
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if (subRightIndex > -1 && subRightIndex > mid) {
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rightIndex = subRightIndex;
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} else {
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rightIndex = mid;
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}
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return new int[]{leftIndex, rightIndex};
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} else if (nums[mid] < target) {
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left = mid + 1;
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} else {
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right = mid - 1;
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}
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}
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// if (leftIndex == -1) {
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// return new int[]{-1, -1};
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// }
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return new int[]{-1, -1};
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}
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public int findLeftIndex(int[] nums, int target, int left, int right) {
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int mid = left + (right - left) / 2;
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int leftIndex = -1;
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int currentLeftIndex = -1;
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if (nums[mid] == target) {
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leftIndex = mid;
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if (leftIndex > 0) {
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if (nums[leftIndex - 1] < target) {
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return leftIndex;
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} else {
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currentLeftIndex = findLeftIndex(nums, target, left, mid - 1);
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if (currentLeftIndex != -1 && currentLeftIndex < leftIndex) {
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leftIndex = currentLeftIndex;
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}
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}
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} else {
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return leftIndex;
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}
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} else if (nums[mid] < target && left < right) {
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return findLeftIndex(nums, target, mid + 1, right);
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} else if (left < right){
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return findLeftIndex(nums, target, left, mid - 1);
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} else {
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return leftIndex;
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}
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return leftIndex;
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}
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public int findRightIndex(int[] nums, int target, int left, int right) {
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int mid = left + (right - left) / 2;
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int rightIndex = -1;
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int currentRightIndex = -1;
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if (nums[mid] == target) {
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rightIndex = mid;
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if (rightIndex < nums.length - 1) {
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if (nums[rightIndex + 1] > target) {
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return rightIndex;
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} else {
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if (mid < right) {
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currentRightIndex = findRightIndex(nums, target, mid + 1, right);
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if (currentRightIndex != -1 && currentRightIndex > rightIndex) {
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rightIndex = currentRightIndex;
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}
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} else {
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return rightIndex;
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}
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}
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} else {
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return rightIndex;
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}
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} else if (nums[mid] < target && left < right && mid < right) {
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return findRightIndex(nums, target, mid + 1, right);
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} else if (left < right && mid > 0){
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return findRightIndex(nums, target, left, mid - 1);
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} else {
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return rightIndex;
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}
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return rightIndex;
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}
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public static void main(String[] args) {
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int[] nums = new int[] {1,4};
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int target = 4;
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int left = 0;
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int right = nums.length - 1;
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Solution0034 solution0034 = new Solution0034();
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int[] res = solution0034.searchRange(nums, target);
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System.out.println(res[0]);
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System.out.println(res[1]);
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}
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}
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