PATAdvanced/1029.c

#include <stdio.h>
#include <limits.h>

int main()
{
	int N1, N2, seq[200001], *p = seq, n, c = 0, median = 0;

	/* Read one sequence into array */
	scanf("%d", &N1);
	for (int i = 0; i < N1; i++)
		scanf("%d", seq + i);
	/* Boundary setup */
	seq[N1] = INT_MAX;

	/* Read the other sequence on the fly while doing merge sort.
	 * This is due to the memory limitation of the problem (1.5MB) */
	scanf("%d", &N2);
	/* read the first one */
	scanf("%d", &n);
	/* just enough to find the median: skip the first half */
	for (int i = 0; i < (N1 + N2 + 1) / 2; i++) {
		/* Record the smallest of the two */
		if (*p < n)
			median = *p;
		else
			median = n;

		/* Either point p at the next number or read a new number into n */
		if ((*p < n && p < seq + N1) || (*p > n && c == N2)) {
			p++;
		} else {
			if (c == N2 - 1)
				n = INT_MAX;
			else
				scanf("%d", &n);
			c++;
		}
	}

	printf("%d", median);

	return 0;
}