leetcode(c++)(二分查找)

#include <iostream>
#include <numeric>
#include <algorithm>
#include <vector>

using namespace std;

double findMediaSorted(const vector<int>&n1,const vector<int>& n2)
{
    int m = n1.size(),n = n2.size();
    if(m > n)return findMediaSorted(n2,n1);
    int left = 0, right = m;
    while(left <= right){
        int x = left + (right - left ) / 2;
        int y = (m + n + 1) / 2 - x;
        int xLeft = (x == 0) ? INT_MIN : n1[x-1];
        int xRight = (x == m) ? INT_MAX : n1[x];
        int yLeft = (y == 0) ? INT_MIN : n2[y-1];
        int yRight = (y == n) ? INT_MAX : n2[y];
        if(xLeft <= yRight && yLeft <= xRight)
        {
            if((m + n) % 2 == 0)return (double)(max(xLeft,yLeft), min(xRight,yRight)) / 2.0;
            else return (double)max(xLeft,yLeft);
        }
        else if(xRight > yLeft) right = x - 1;
        else left = x + 1;
    }
    return -1;
}

bool valid(const vector<int>& nums,int m, int sum)
{
    int curSum = 0, cnt = 1;
    for(auto num : nums)
    {
        curSum += num;
        if(curSum > sum)
        {
            curSum = num;
            ++cnt;
            if(cnt > m)return false;
        }
    }
    return true;
}

int binary(const vector<int>& nums,int m, int low,int high)
{
    while(low <= high)
    {
        int mid = low + (high - low) / 2;
        if(valid(nums,m,mid))high = mid - 1;
        else low = mid + 1;
    }
    return low;
}

int splitArray(const vector<int>& nums, int m)
{
    int sum = accumulate(nums.begin(),nums.end(),0);
    int maxVal = *(max_element(nums.begin(),nums.end()));  
    return binary(nums,m,maxVal,sum);
}

bool check(int x, vector<int>& position,int m)
{
    int pre = position[0],cnt = 1;
    for(int i = 1; i < position.size(); ++i)
    {
        if(position[i] - pre >= x)
        {
            pre = position[i];
            ++cnt;
        }
    }
    return cnt >= m;
}

int maxDistance(vector<int>& position,int m)
{
    sort(position.begin(),position.end());
    int left = 1, right = position.back() - position[0],res = -1;
    while(left <= right)
    {
        int mid = left + (right - left ) / 2;
        if(check(mid,position,m))
        {
            res = mid;
            left = mid + 1;
        }
        else
        {
            right = mid - 1;
        }
    }    
    return res;
}

int main()
{

    //LeetCode4
    vector<int>nums1{1,3};
    vector<int>nums2{2};
    cout << findMediaSorted(nums1,nums2) << endl;

    //LeetCode410
    vector<int> nums{7,2,5,10,8};
    int m = 2;
    cout << splitArray(nums,m) << endl;

    //LeetCode1552
    nums = {1,2,3,4,7};
    m = 3;    
    cout << maxDistance(nums,m) << endl;


    return 0;
}