34. Search for a Range

1刷
还是二分查找的练习，学会lower_bound和upper_bound的方法果然一次AC！！！
Important！！！

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        vector<int>se;
        int len = nums.size();
        int first = 0;
        while(len > 0){
            int half = len >> 1;
            int mid = first + half;
            if(nums[mid] < target){
                first = mid + 1;
                len = len - half - 1;
            }
            else
                len = half;
        }
        if(first == nums.size()){
            se.push_back(-1);
            se.push_back(-1);
            return se;
        }
        else if(nums[first] != target){
            se.push_back(-1);
            se.push_back(-1);
            return se;
        }

        se.push_back(first);
        first = 0;
        len = nums.size();
        while(len > 0){
            int half = len >> 1;
            int mid = first + half;
            if(nums[mid] > target)
                len = half;
            else{
                first = mid + 1;
                len = len - half - 1;
            }
        } 

        se.push_back(first - 1);
        return se;
    }
};

这题要3刷，超级好题！用来复习无敌2分，2分还有一个模板需要练习就是就求最小值，上一题还是上上提有。

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        vector<int>ve;


        int first = 0, middle;
        int half, len = nums.size();

        while(len > 0){
            half = len >> 1;
            middle = first + half;
            if(nums[middle] < target){
                first = middle + 1;
                len = len - half - 1;
            }
            else len = half;
        }

        if(nums.size() == 0 || first >= nums.size() || nums[first] != target){
            ve.push_back(-1);
            ve.push_back(-1);
            return ve;
        }
        ve.push_back(first);

        first = 0;
        len = nums.size();

        while(len > 0){
            half = len >> 1;
            middle = first + half;
            if(nums[middle] > target){
                len = half;
            }
            else{
                first = middle + 1;
                len = len - half - 1;
            }
        }
        ve.push_back(first - 1);
        return ve;
    }
};