leetcode(c++)(前缀和)

#include <iostream>
#include <vector>
#include <unordered_map>
#include <queue>
using namespace std;

int subarraySum(const vector<int>& nums,int target)
{
    unordered_map<int,int>map;
    int sum = 0, res = 0;
    map[0] = 1;
    for(int num:nums)
    {
        sum += num;
        if(map.count(sum - target))res+=map[sum - target];
        ++map[sum];
    }
    return res;
}

int subarrayDivByK(const vector<int>& nums,int k)
{
    unordered_map<int,int>map;
    map[0] = 1;
    int prefix = 0,res = 0;
    for(int num:nums)
    {
        prefix = (prefix + num % k + k) % k;
        res += map[prefix];
        ++map[prefix];
    }
    return res;
}

bool checkSubArraySum(const vector<int>& nums, int k)
{
    int sum = 0;
    unordered_map<int,int>map;
    map[0] = -1;
    for(int i = 0; i < nums.size(); ++i)
    {
        sum += nums[i];
        if(k != 0)sum %= k;
        if(map.count(sum))
        {
            if(i - map[sum] > 1)return true;
        }
        else
        {
            map[sum] = i;
        }
    }
    return false;
}

int findMaxLen(vector<int>& nums)
{
    for(int i = 0; i < nums.size(); ++i)
    {
        if(nums[i] == 0)nums[i] = -1;
    }
    int res = 0,sum = 0;
    unordered_map<int,int>map;
    map[0] = -1;
    for(int i = 0; i < nums.size(); ++i)
    {
        sum += nums[i];
        if(map.count(sum)) res = max(res,i-map[sum]);
    }    
    return res;
}

vector<int>getModifiedArray(int length, const vector<vector<int>>& updates)
{
    vector<int>res(length,0);
    for(auto update:updates)
    {
        int val = update[2];
        int start = update[0];
        int end = update[1];
        res[start]+=val;
        if(end < length - 1)res[end + 1]-=val;
    }
    int sum = 0;
    for(int i = 0; i < length; ++i)
    {
        sum += res[i];
        res[i] = sum;
    }
    return res;
}

void print(const vector<int>& nums)
{
    for(int num : nums)
    {
        cout << num << " ";
    }
    cout << endl;
}

int minSubArrayLen(const vector<int>& nums,int target)
{
    int left = 0, n = nums.size(), res = INT_MAX, sum = 0;
    for(int i = 0; i < n; ++i)
    {
        sum += nums[i];
        while(sum >= target)
        {
            res = min(res,i - left + 1);
            sum -= nums[left++];
        }
    }
    return res == INT_MAX ? 0 : res;
}

int shortestSubarray(const vector<int>&A,int k)
{
    int n = A.size(), res = n + 1;
    vector<int>sum(n+1);
    for(int i = 0; i < n; ++i)
    {
        sum[i+1] = sum[i] + A[i];
    }
    deque<int>q;
    for(int i = 0; i < n + 1; ++i)
    {
        while(!q.empty() && sum[q.front()] >= sum[i])q.pop_back();
        while(!q.empty() && sum[i] - sum[q.front()] >= k)
        {
            res = min(res,i - q.front());
            q.pop_front();
        }
        q.push_back(i);
    }
    return res <= n ? res : -1;
}

int main()
{
    //LeetCode560
    vector<int>nums{1,2,3};
    int k = 3;
    cout << subarraySum(nums,k) << endl;

    //LeetCode974
    nums={4,5,0,-2,-3,1};
    k = 5;
    cout << subarrayDivByK(nums,k) << endl;

    //LeetCode523
    nums = {23,2,4,6,7};
    k = 6;
    cout << checkSubArraySum(nums,k) << endl;

    //LeetCode525
    nums = {0,1,0};
    cout << findMaxLen(nums) << endl;

    //LeetCode370
    int len = 5;
    vector<vector<int>>updates{{1,3,2},{2,4,3},{0,2,-2}};
    print(getModifiedArray(len,updates));

    //LeetCode209
    int target = 7;
    nums = {2,3,1,2,4,3};
    cout << minSubArrayLen(nums,target) << endl;

    //LeetCode862
    nums = {2,-1,2};
    k = 3;
    cout << shortestSubarray(nums,k) << endl;
    return 0;
}