Codeforces 21C Stripe 2 卧槽，出题人母语绝对不是English啊 - c++编程基础

sum = sigma num[i] (1 <= i <= n)。

s[i] = sigam num[j] (1<= j <= i)。

找到所有满足s[i]*2 =sum-s[i] ，s[i] = 2*(sum-s[i])。然后枚举累加一下。

卧槽，可是题意里明明说每个 piece 里都要有positive interge。

可是去了这个限制就过了啊。

#include 
  
   
#include 
   
     #include 
    
      #include 
     
       #include 
      
        #include 
       
         #include 
        
          #include 
         
           #include 
           #include 
           
             #include 
            
              #pragma comment(linker, "/STACK:1024000000"); #define EPS (1e-6) #define _LL long long #define ULL unsigned long long #define LL __int64 #define INF 0x3f3f3f3f #define Mod 1000000007 /** I/O Accelerator Interface .. **/ #define g (c=getchar()) #define d isdigit(g) #define p x=x*10+c-'0' #define n x=x*10+'0'-c #define pp l/=10,p #define nn l/=10,n template
             
               inline T& RD(T &x) { char c; while(!d); x=c-'0'; while(d)p; return x; } template
              
                inline T& RDD(T &x) { char c; while(g,c!='-'&&!isdigit(c)); if (c=='-') { x='0'-g; while(d)n; } else { x=c-'0'; while(d)p; } return x; } inline double& RF(double &x) //scanf("%lf", &x); { char c; while(g,c!='-'&&c!='.'&&!isdigit(c)); if(c=='-')if(g=='.') { x=0; double l=1; while(d)nn; x*=l; } else { x='0'-c; while(d)n; if(c=='.') { double l=1; while(d)nn; x*=l; } } else if(c=='.') { x=0; double l=1; while(d)pp; x*=l; } else { x=c-'0'; while(d)p; if(c=='.') { double l=1; while(d)pp; x*=l; } } return x; } #undef nn #undef pp #undef n #undef p #undef d #undef g using namespace std; LL num[100010]; LL ans[2][100010] = {{0},{0}}; LL sum[2][100010] = {{0},{0}}; LL dis[100010] = {0}; int mark[2][100010] = {{0},{0}}; int main() { int n; scanf("%d",&n); int i; for(i = 1;i <= n; ++i) scanf("%I64d",&num[i]); for(i = 1;i <= n; ++i) sum[0][i] = sum[0][i-1] + num[i]; for(i = n;i >= 1; --i) sum[1][i] = sum[1][i+1] + num[i]; for(i = 1;i <= n; ++i) ans[0][i] = ans[0][i-1] + (num[i] >= 0 ? 1 : 0); for(i = n;i >= 1; --i) ans[1][i] = ans[1][i+1] + (num[i] >= 0 ? 1 : 0); LL S = sum[0][n]; for(i = 1;i <= n; ++i) if(sum[0][i]*2 == S-sum[0][i] ) mark[0][i] = 1; for(i = n;i >= 1; --i) if(sum[1][i]*2 == S-sum[1][i]) mark[1][i] = 1; for(i = 1;i <= n; ++i) dis[i] = dis[i-1] + mark[0][i]; LL anw = 0; for(i = 2;i <= n; ++i) if(mark[1][i]) anw += dis[i-2]; printf("%I64d\n",anw); return 0; }