joyoi tyvj1313 [NOIP2010初赛]烽火传递

单调队列优化dp

#include <iostream>
#include <cstdio>
using namespace std;
int dp[1000005], n, m, q[1000005], l, r, w[1000005];
//dp[i] = dp[j] + w[i] | i-m<=j<=i-1
int main(){
	cin>>n>>m;
	for(int i=1; i<=n; i++)	scanf("%d", &w[i]);
	for(int i=1; i<=n; i++){
		while(l<=r && q[l]<i-m)	l++;
		dp[i] = dp[q[l]] + w[i];
		while(l<=r && dp[q[r]]>dp[i])	r--;
		q[++r] = i;
	}
	int minn=0x3f3f3f3f;
	for(int i=n-m+1; i<=n; i++)
		minn = min(minn, dp[i]);
	cout<<minn<<endl;
	return 0;
}