rt.后面两个点没过

#include <bits/stdc++.h>
#define N 100010
#define ll long long
using namespace std;
ll a[N];
ll n,x,ans;
int main(){
	scanf("%lld %lld",&n,&x);
	for(ll i=1;i<=n;i++){
		scanf("%lld",&a[i]);
	}
	for(ll i=1;i<=n-1;i++){
		ll sum=a[i]+a[i+1];
		if(sum>x){
			ans+=(sum-x);
			a[i+1]-=(sum-x);
		}
	}
	printf("%lld",ans);
	return 0;
}

玄关！