JOI2007本選 問題1＠C++

瞬殺。というかそうじゃないとまずいよね。

#include <climits>
#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

int main(int argc, char *argv[], char *envp[])
{
	#ifdef DEBUG
	FILE *in = stdin;
	FILE *out = stdout;
	#else
	FILE *in = fopen("input.txt", "r");
	FILE *out = fopen("output.txt", "w");
	#endif
	int n;
	int k;
	fscanf(in, "%d %d\n", &n, &k);
	vector<int> a(n);
	for(int i=0;i<n;i++) {
		fscanf(in, "%d\n", &a[i]);
	}
	int subsum = 0;
	int max_sum = INT_MIN;
	for(int i=0;i<k;i++) {
		subsum += a[i];
	}
	for(int i=k;i<n;i++) {
		max_sum = max(max_sum, subsum);
		subsum += a[i];
		subsum -= a[i-k];
	}
	max_sum = max(max_sum, subsum);
	fprintf(out, "%d\n", max_sum);
	fclose(in);
	fclose(out);
	return 0;
}