class Solution {
    public boolean carPooling(int[][] trips, int capacity) {
        int[] diff = new int[1001]; // 记录每个站点改变的人数，比如增加几个人，减少几个人
        for(int[] trip : trips){
            int cnt = trip[0];
            int from = trip[1];
            int to = trip[2];
            diff[from] += cnt;
            diff[to] -= cnt;
        }
        int num = 0; // 记录每个站点车上的人数
        for(int i = 0; i < 1001; i++){
            num += diff[i];
            if(num > capacity){
                return false;
            }
        }
        return true;
    }
}

class Solution {
    public int[] corpFlightBookings(int[][] bookings, int n) {
        int[] diff = new int[n];
        int m = bookings.length;
        for(int i = 0; i < m; i++){
            int l = bookings[i][0];
            int r = bookings[i][1];
            int cnt = bookings[i][2];
            diff[l - 1] += cnt;
            if(r < n) diff[r] -= cnt;
        }
        for(int i = 1; i < n; i++){
            diff[i] += diff[i - 1];
        }
        return diff;
    }
}

class NumArray {
    int n;
    int[] pre;

    public NumArray(int[] nums) {
        n = nums.length;
        pre = new int[n];
        pre[0] = nums[0];
        for(int i = 1; i < n; i++){
            pre[i] = pre[i - 1] + nums[i];
        }
    }
    
    public int sumRange(int l, int r) {
        if(l == 0) return pre[r];
        return pre[r] - pre[l - 1];
    }
}

class Solution {
    public int subarraySum(int[] nums, int k) {
        // 也就是前缀和数组两数之差为k
        int n = nums.length;
        int[] pre = new int[n];
        pre[0] = nums[0];
        for(int i = 1; i < n; i++){
            pre[i] = pre[i - 1] + nums[i];
        }
        int ans = 0;
        // presum, cnt
        HashMap<Integer, Integer> map = new HashMap<>();
        map.put(0, 1);   // 表示pre[i]就是k，即[0,i]和为k
        for(int i = 0; i < n; i++){
            if(map.containsKey(pre[i] - k)){
                ans += map.get(pre[i] - k);
            }
            map.put(pre[i], map.getOrDefault(pre[i], 0) + 1);
        }
        return ans;
    }
}

class Solution {
    public boolean checkSubarraySum(int[] nums, int k) {
        int n = nums.length;
        int[] pre = new int[n];
        pre[0] = nums[0];
        for(int i = 1; i < n; i++){
            pre[i] = pre[i - 1] + nums[i];
        }
        HashMap<Integer, Integer> map = new HashMap<>();
        map.put(0, -2); // 如果前缀和数组 某个数 % k 的余数就是0，说明[0, i]区间的和就是k的整数倍，下标设置为-2
        for(int i = 0; i < n; i++){
            if(map.containsKey(pre[i] % k)){
                if(i > 0 && i - map.get(pre[i] % k) >= 2){
                    // 同余的同时，还需要满足i > 0，因为i == 0时数组长度是1
                    return true;
                }
            }else{
                // 余数已经出现过了，就不再更新了
                map.put(pre[i] % k, i);
            }
        }
        return false;
    }
}