9b.c (809B)
1 #include <inttypes.h> 2 #include <stdbool.h> 3 #include <stdio.h> 4 #include <stdlib.h> 5 6 #define N 1000 7 8 #define isnum(c) (c == '-' || (c >= '0' && c <= '9')) 9 10 int64_t readl(int64_t nums[], char *buf) { 11 int64_t i; 12 for (i = 0; *buf; buf++) { 13 if (!isnum(*buf)) continue; 14 nums[i++] = atoll(buf); 15 while (isnum(*buf)) buf++; 16 } 17 return i; 18 } 19 20 bool isconstant(int64_t a[], int n) { 21 for (int i = 0; i < n-1; i++) 22 if (a[i] != a[i+1]) 23 return false; 24 return true; 25 } 26 27 int64_t next(int64_t a[], int64_t n) { 28 int64_t x = a[0]; 29 if (isconstant(a, n)) 30 return x; 31 for (int i = 0; i < n-1; i++) 32 a[i] = a[i+1] - a[i]; 33 return x - next(a, n-1); 34 } 35 36 int main() { 37 char line[N]; 38 int64_t s, a[N]; 39 40 for (s = 0; fgets(line, N, stdin) != NULL; ) 41 s += next(a, readl(a, line)); 42 43 printf("%" PRId64 "\n", s); 44 return 0; 45 }