力扣labuladong——一刷day20

最新推荐文章于 2025-12-10 14:25:37 发布

原创最新推荐文章于 2025-12-10 14:25:37 发布 · 545 阅读

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#leetcode #算法 #java #数据结构

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文章介绍了如何使用差分数组工具类处理LeetCode中的三个问题：区间加法、航班预订统计和拼车。该工具类简化了频繁对数组区间元素的增减操作。

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文章目录

前言
差分数组工具类
一、力扣370. 区间加法
二、力扣1109. 航班预订统计
三、力扣1094. 拼车

前言

差分数组的主要适用场景是频繁对原始数组的某个区间的元素进行增减
这里提供一个工具类方便大家使用

差分数组工具类

class Difference{
    private int[] diff;
    public Difference(int[] nums){
        diff = new int[nums.length];
        diff[0] = nums[0];
        for(int i = 1; i < nums.length; i ++){
            diff[i] = nums[i] - nums[i-1];
        }
    }
    public void increment(int low, int high, int val){
        diff[low] += val;
        if(high < diff.length-1){
            diff[high+1] -= val;
        }
    }
    public int[] result(){
        int[] res = new int[diff.length];
        res[0] = diff[0];
        for(int i = 1; i < diff.length; i ++){
            res[i] = res[i-1] + diff[i];
        }
        return res;
    }
}

一、力扣370. 区间加法

class Solution {
    public int[] getModifiedArray(int length, int[][] updates) {
        int[] res = new int[length];
        Difference diff = new Difference(res);
        for(int i = 0; i < updates.length; i ++){
            diff.increment(updates[i][0],updates[i][1],updates[i][2]);
        }
        res = diff.result();
        return res;
    }
}
class Difference{
    private int[] diff;
    public Difference(int[] nums){
        diff = new int[nums.length];
        diff[0] = nums[0];
        for(int i = 1; i < nums.length; i ++){
            diff[i] = nums[i] - nums[i-1];
        }
    }
    public void increment(int low, int high, int val){
        diff[low] += val;
        if(high < diff.length-1){
            diff[high+1] -= val;
        }
    }
    public int[] result(){
        int[] res = new int[diff.length];
        res[0] = diff[0];
        for(int i = 1; i < diff.length; i ++){
            res[i] = res[i-1] + diff[i];
        }
        return res;
    }
}

二、力扣1109. 航班预订统计

class Solution {
    public int[] corpFlightBookings(int[][] bookings, int n) {
        int[] res = new int[n];
        Difference diff = new Difference(res);
        for(int i = 0; i < bookings.length; i ++){
            diff.increase(bookings[i][0]-1,bookings[i][1]-1,bookings[i][2]);
        }
        res = diff.result();
        return res;
    }
}
class Difference{
    private int[] diff;
    public Difference(int[] nums){
        diff = new int[nums.length];
        diff[0] = nums[0];
        for(int i = 1; i < nums.length; i ++){
            diff[i] = nums[i] - nums[i-1];
        }
    }
    public void increase(int low,int high, int val){
        diff[low] += val;
        if(high + 1 < diff.length){
            diff[high+1] -= val;
        }
    }
    public int[] result(){
        int[] res = new int[diff.length];
        res[0] = diff[0];
        for(int i = 1; i < diff.length; i ++){
            res[i] = res[i-1] + diff[i];
        }
        return res;
    }
}

三、力扣1094. 拼车

class Solution {
    public boolean carPooling(int[][] trips, int capacity) {
        int[] res = new int[1001];
        Difference diff = new Difference(res);
        for(int i = 0; i < trips.length; i ++){
            diff.increase(trips[i][1],trips[i][2]-1,trips[i][0]);
        }
        res = diff.result();
        for(int i = 0; i < res.length; i ++){
            if(res[i] > capacity){
                return false;
            }
        }
        return true;
    }
}
class Difference{
    private int[] diff;
    public Difference(int[] nums){
        diff = new int[nums.length];
        diff[0] = nums[0];
        for(int i = 1; i < nums.length; i ++){
            diff[i] = nums[i] - nums[i-1];
        }
    }
    public void increase(int low, int high, int val){
        diff[low] += val;
        if(high + 1 < diff.length){
            diff[high+1] -= val;
        }
    }
    public int[] result(){
        int[] res = new int[diff.length];
        res[0] = diff[0];
        for(int i = 1; i < diff.length; i ++){
            res[i] = res[i-1] + diff[i];
        }
        return res;
    }
}