一维差分、二维差分

一维

int a[maxn],b[maxn];

void insert(int l,int r,int c)   //[l,r]同时加c
{
	b[l]+=c;
	b[r+1]-=c;
}

二维

int a[maxn][maxn], b[maxn][maxn];

void insert(int x1,int y1,int x2,int y2,int c) //[x1,y1] - [x2,y2]同时加c
{
    b[x1][y1] += c;
    b[x1][y2+1] -=c;
    b[x2+1][y1] -=c;
    b[x2+1][y2+1] +=c;
}