CF660C Hard Process 题解

Solution

一眼 $\mathcal{O}(n)$ 吊打 $\mathcal{O}(n \log n)$。

求个前缀和，然后双指针去移动，求最大值。

int	qzh[N][2], a[N];
int maxx = 0, ansl, ansr;
int f = 0;
 
int cnt = 0;
 
signed main() 
{
	int n = read(), k = read();	
	for(int i = 1; i <= n; i++) a[i] = read();
	for(int i = 1; i <= n; i++) {
		if(a[i] == 1) cnt++, maxx = max(cnt, maxx);
		else maxx = max(cnt, maxx), cnt = 0;
	}
	for(int i = 1; i <= n; i++) {
		if(a[i]) qzh[i][1] = qzh[i - 1][1] + 1, qzh[i][0] = qzh[i - 1][0];
		else qzh[i][0] = qzh[i - 1][0] + 1, qzh[i][1] = qzh[i - 1][1];
	}
	int l = 1, r = 1;
	while(l <= r && r <= n) {
		if(qzh[r][0] - qzh[l - 1][0] <= k) {
			if(maxx < r - l + 1) {
				maxx = r - l + 1;
				ansl = l, ansr = r;
			}
			r++;
		}
		else l++;
	}
	if(k) for(int i = ansl; i <= ansr; i++) a[i] = 1;
	printf("%d\n", maxx);
	for(int i = 1; i <= n; i++) printf("%d ", a[i]);
	return 0;
}