1094. 拼车

English Version

题目描述

车上最初有 capacity 个空座位。车 只能 向一个方向行驶（也就是说，不允许掉头或改变方向）

给定整数 capacity 和一个数组 trips ,  trip[i] = [numPassengersi, fromi, toi] 表示第 i 次旅行有 numPassengersi 乘客，接他们和放他们的位置分别是 fromi 和 toi 。这些位置是从汽车的初始位置向东的公里数。

当且仅当你可以在所有给定的行程中接送所有乘客时，返回 true，否则请返回 false。

 

示例 1：

输入：trips = [[2,1,5],[3,3,7]], capacity = 4
输出：false

示例 2：

输入：trips = [[2,1,5],[3,3,7]], capacity = 5
输出：true

 

提示：

• 1 <= trips.length <= 1000
• trips[i].length == 3
• 1 <= numPassengersi <= 100
• 0 <= fromi < toi <= 1000
• 1 <= capacity <= 105

解法

差分数组。

Python3

class Solution:
    def carPooling(self, trips: List[List[int]], capacity: int) -> bool:
        delta = [0] * 1001
        for num, start, end in trips:
            delta[start] += num
            delta[end] -= num
        return all(s <= capacity for s in accumulate(delta))

Java

class Solution {
    public boolean carPooling(int[][] trips, int capacity) {
        int[] delta = new int[1001];
        for (int[] trip : trips) {
            int num = trip[0], start = trip[1], end = trip[2];
            delta[start] += num;
            delta[end] -= num;
        }
        int cur = 0;
        for (int num : delta) {
            cur += num;
            if (cur > capacity) {
                return false;
            }
        }
        return true;
    }
}

JavaScript

/**
 * @param {number[][]} trips
 * @param {number} capacity
 * @return {boolean}
 */
var carPooling = function (trips, capacity) {
    let delta = new Array(1001).fill(0);
    for (let [num, start, end] of trips) {
        delta[start] += num;
        delta[end] -= num;
    }
    let s = 0;
    for (let num of delta) {
        s += num;
        if (s > capacity) {
            return false;
        }
    }
    return true;
};

C++

class Solution {
public:
    bool carPooling(vector<vector<int>>& trips, int capacity) {
        vector<int> delta(1001);
        for (auto &trip : trips) {
            int num = trip[0], start = trip[1], end = trip[2];
            delta[start] += num;
            delta[end] -= num;
        }
        int cur = 0;
        for (auto &num : delta) {
            cur += num;
            if (cur > capacity) {
                return false;
            }
        }
        return true;
    }
};

Go

func carPooling(trips [][]int, capacity int) bool {
	delta := make([]int, 1010)
	for _, trip := range trips {
		num, start, end := trip[0], trip[1], trip[2]
		delta[start] += num
		delta[end] -= num
	}
	cur := 0
	for _, num := range delta {
		cur += num
		if cur > capacity {
			return false
		}
	}
	return true
}

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