题解：luogu U37449 Lycanthropy

差分套差分qwq

pushinl说这题思维比较好

其实算是比较简单了

一开始写了假的差分

还是没摆脱单个处理

其实是对每个区间边界进行差分处理，每个区间内部再进行标记差分

正解很好理解

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int pls=40001;
int a[20000050];
long long bl, tot;
void change(int l, int r, int val){
    a[l+pls]+=val;
    a[r+1+pls]-=val;
}
int main(){
    int n,m;
    scanf("%d%d", &n, &m);
    for (int i=1; i<=n; ++i){
        int v, x;
        scanf("%d%d", &v, &x);
        change(x-v+1, x, -1);
        change(x+1, x+v, 1);
        change(x-3*v+1, x-2*v, 1);
        change(x-2*v+1, x-v, -1);
        change(x+v+1, x+2*v, 1);
        change(x+2*v+1, x+3*v, -1);
    }
    for (int i=1; i<=m+pls; ++i){
        bl+=a[i];
        tot+=bl;
        if(i>pls)   printf("%lld ", tot);
    }
    printf("
");
    return 0;
}