不成熟的梦想家 (未熟DREAMER)

不成熟的梦想家

由于区间更改不会影响区间内点的相对大小，只要维护x和y+1两个点即可，注意y==n时不用修改

#include 
using namespace std;
int a[200005];
long long f[2000005];
int read(){
	int x = 0,dign = 1;
	char c = getchar();
	while(c<'0'||c>'9'){
		if(c=='-')dign=-1;
		c = getchar();
	}
	while(c>='0'&&c<='9'){
		x = 10*x+c-'0';
		c = getchar();
	}
	return x*dign;
}

int main()
{
	int n,s,t,q; long long b =0;
	n = read(); q = read(); s = read(); t = read();
	
	for(int i=0;i<=n;i++){
		scanf("%d",&a[i]);
		if(i>=1)f[i] = a[i] - a[i-1];
		b+= f[i]*(f[i] > 0 ? -s : -t);
	} 
	int x,y,z;
	while(q--){
		x = read(); y = read(); z = read();
		b-= f[x]*(f[x] > 0 ? -s : -t);
		b+= (f[x]+z)*( f[x]+z > 0 ? -s : -t );
		f[x]+=z;
		if(y!=n){
		b-= f[y+1]*(f[y+1] > 0 ? -s : -t);
		b+= (f[y+1]-z)*( f[y+1]-z > 0 ? -s : -t );
		f[y+1]-=z;
		}		
		printf("%lld\n",b);
	} 
	
	return 0;
 }