1 #include<cstdio> 2 #define MAXN 100010 3 #define MIN(a,b) ((a)<(b)?(a):(b)) 4 typedef __int64 LL; 5 LL limit,a[MAXN],dp[MAXN]; 6 int n,Q[MAXN]; 7 LL DoIt() 8 { 9 LL sum; 10 int i,j,k,front,rear; 11 for(i=1;i<=n;i++) 12 { 13 if(a[i]>limit) 14 return -1; 15 } 16 sum=dp[0]=0; 17 front=0; 18 rear=-1; 19 for(i=k=1;i<=n;i++) 20 { 21 sum+=a[i]; 22 for(;sum>limit;k++) 23 sum-=a[k]; 24 for(;front<=rear&&Q[front]<k;front++); 25 for(;front<=rear&&a[Q[rear]]<=a[i];rear--); 26 Q[++rear]=i; 27 dp[i]=dp[k-1]+a[Q[front]]; 28 for(j=front;j<rear;j++) 29 dp[i]=MIN(dp[i],dp[Q[j]]+a[Q[j+1]]); 30 } 31 return dp[n]; 32 } 33 int main() 34 { 35 int i; 36 while(~scanf("%d%I64d",&n,&limit)) 37 { 38 for(i=1;i<=n;i++) 39 scanf("%I64d",&a[i]); 40 printf("%I64d\n",DoIt()); 41 } 42 return 0; 43 }
