题意：
给出序列 a[] 的其中几项 ，已知序列满足非减，并且 0 <= ai <= 100， 问 (a1 + a2) / ( ∑ai)最大可能是多少
分析：
保证 a1,a2尽可能大， 其余尽可能小即可
1 #include <iostream> 2 #include <cstring> 3 using namespace std; 4 int t, n, m; 5 int a[105]; 6 int GCD(int a, int b) 7 { 8 return b == 0? a : GCD(b, a % b); 9 } 10 int main() 11 { 12 scanf("%d", &t); 13 while (t--) 14 { 15 memset(a, -1, sizeof(a)); 16 scanf("%d%d", &n, &m); 17 if (m == 0 || n == 2) 18 { 19 puts("1/1"); continue; 20 } 21 for (int i = 1; i <= m; i++) 22 { 23 int x, y; 24 scanf("%d%d", &x, &y); 25 a[x] = y; 26 } 27 int Min=0; 28 for (int i = n; i > 2; i--) 29 { 30 if (a[i] == -1) a[i] = Min; 31 else Min = a[i]; 32 } 33 if (a[1] == -1) a[1] = 100; 34 if (a[2] == -1) a[2] = a[1]; 35 int tu = a[1] + a[2], td = 0; 36 for (int i = 1; i <= n; i++) td += a[i]; 37 int gcd = GCD(tu, td); 38 tu /= gcd; 39 td /= gcd; 40 printf("%d/%d ", tu, td); 41 } 42 }