【AcWing】差分及其应用

#include<iostream>
using namespace std;
const int N = 1e5 + 10;
int a[N], b[N];
int main()
{
    int n, m;
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
    {
        scanf("%d", &a[i]);
        b[i] = a[i] - a[i - 1];      //构建差分数组
    }
    int l, r, c;
    while (m--)
    {
        scanf("%d%d%d", &l, &r, &c);
        b[l] += c;     //将序列中[l, r]之间的每个数都加上c
        b[r + 1] -= c; //因为是差分，所以只需要看一下序列的开头和结尾即可
    }                  //开头加一，那么从开头到后面的序列都加一
    for (int i = 1; i <= n; i++)
    {
        a[i] = b[i] + a[i - 1];    //前缀和运算
        printf("%d ", a[i]);
    }
    return 0;
}

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 100010;
typedef long long LL;
int n;
int a[N], b[N];
int main()
{
    scanf("%d", &n);
    for (int i = 1; i <= n; i ++ ) scanf("%d", &a[i]);
    for (int i = 1; i <= n; i ++ ) b[i] = a[i] - a[i - 1];//差分数组
    LL p = 0, q = 0;
    for (int i = 2; i <= n; i ++ )
        if (b[i] > 0) p += b[i];//正数加上去
        else q -= b[i];         //负数先变成正数，再加上去
    cout << max(p, q) << endl;//因为得保证所有项大小一样，所以是max而不是min
    cout << abs(p - q) + 1 << endl;
    return 0;
}