Bestcoder round #8

Summary

 1 /* 2 ID:esxgx1 3 LANG:C++ 4 PROG:bestcoder8_A 5 */ 6 #include <cstdio> 7 #include <cstring> 8 #include <iostream> 9 #include <algorithm>10 using namespace std;11 12 int a[107];13 long long b[107*107];14 15 int main(void)16 {17     #ifndef ONLINE_JUDGE18     freopen("in.txt", "r", stdin);19     #endif20 21     int N;22     while(scanf("%d", &N) > 0) {23         for(int i=0; i<N; ++i) scanf("%I64d", &a[i]);24         int k = 0;25         for(int i=0; i<N; ++i) {26             for(int j=i+1; j<N; ++j) {27                 b[k++] = a[i] + a[j];28             }29         }30         sort(b, b+k);31         int j = unique(b, b+k) - b;32         long long S = 0;33         for(int i=0; i<j; ++i) {34             S += b[i];35         }36         printf("%I64d\n", S);37     }38     return 0;39 }

 

Reading Comprehension

 1 /* 2 ID:esxgx1 3 LANG:C++ 4 PROG:bestcoder8_B 5 */ 6 #include <cstdio> 7 #include <cstring> 8 #include <iostream> 9 #include <algorithm>10 using namespace std;11 12 int M;13 14 const int n = 2;15 struct mat {16     int at[n][n];17 };18 19 #define mod M20 mat m22_m(const mat &a,const mat &b)21 {22     mat t;23     for(int i=0;i<n;++i) {24         for(int k=0;k<n;++k) {25             long long u = 0;26             for(int j=0;j<n;++j)27                 u += (long long)a.at[i][j] * b.at[j][k];28             t.at[i][k] = u % mod;29         }30     }31     return t;32 }33 34 mat expo(mat p,int k)35 {36     mat e;37     memset(e.at,0,sizeof(e.at));38     for(int i=0; i<n; ++i) e.at[i][i]=1;39     for(;k; k>>=1) {40         if(k & 1) e = m22_m(e, p);41         p = m22_m(p,p);42     }43     return e;44 }45 46 inline void DEC(int &a, int b){a -= b; if (a < 0) a += M;}47 48 int main(void)49 {50     #ifndef ONLINE_JUDGE51     freopen("in.txt", "r", stdin);52     #endif53 54     int N;55     while(scanf("%d%d", &N, &M)>=0) {56         mat p;57         p.at[0][0] = 1, p.at[0][1] = 2;58         p.at[1][0] = 1, p.at[1][1] = 0;59         int rslt = expo(p, N).at[0][0];60         if (!(N&1)) DEC(rslt, 1);61         printf("%d\n", rslt);62     }63     return 0;64 }

 

Bestcoder round #8