Leetcode_34 寻找目标数字在数组里面的范围

Ding_xiaofei

于 2018-08-14 14:54:15 发布

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分类专栏：编码 Leetcode

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该博客主要介绍了LeetCode第34题的解决方案，通过Java编程语言实现。博主分享了自己尝试解决问题时遇到的错误及参考答案的思路，适合学习LeetCode和Java编程的读者参考。

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题目描述

java

我写的垃圾代码，中间还出错了好几次。

class Solution {
    public int[] searchRange(int[] nums, int target) {

        int[] ret = {-1,-1};
        int l = 0;
        int r = nums.length-1;

        while(l<=r)
        {
             int mid = l+(r-l)/2;
            int n = nums[mid];
            if(n<target)
                l = mid+1;
            else 
                if(n>=target) {
                r = mid - 1;
                if(n == target)
                    ret[0] = mid;
            }

        }

        int l1 = 0;
        int r1 = nums.length-1;   
        while(l1<=r1)
        {
            int mid1 = l1+(r1-l1)/2;
            int n = nums[mid1];
            if(n>target)
                r1 = mid1-1;
            else if(n<=target) {
                l1 = mid1 + 1;
                if(n == target)
                    ret[1] = mid1;
            }
        }
        return ret;


    }
}

参考答案的代码

class Solution {
    public int[] searchRange(int[] nums, int target) {

        int[] ret = {-1,-1};

        int l = 0;
        int r = nums.length-1;
        while(l<r)
        {
            int mid = l+(r-l)/2;
            if(nums[mid]<target)
                l = mid+1;
            else
                r = mid;
        }
        if(nums[l]!=target)
            return ret;
        else
            ret[0] = l;

        r = nums.length-1;
        while(l<r)
        {
            int mid = l+(r-l)/2+1;
            // Make mid biased to the right
            if (nums[mid]>target)
                r = mid-1;
            else
                l = mid;

        }
        ret[1] = r;

        return ret;
    }
}