d
unknown
c_cpp
a year ago
588 B
5
Indexable
#include <stdio.h> int main() { int n, k; scanf("%d %d", &n, &k); int arr[n],exists[n+1]; for (int i = 0; i < n; i++) scanf("%d", &arr[i]); for (int i = 0; i < n+1; i++) exists[i] = 0; for (int i = 0; i < n; i++) exists[arr[i]] = 1; int l = 1, r = n; while (l < r) { if (!exists[l] && !exists[r] && l + r == k) { printf("yes\n"); return 0; } if (l + r < k) l++; else r--; } printf("no\n"); return 0; }
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