Codeforces Round #393 (Div. 2) (8VC Venture Cup 2017 - Final Round Div. 2 Edition) D - Travel Card

D - Travel Card

思路：dp，类似于单调队列优化。

其实可以写的更简单。。。

#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define pii pair<int, int>

using namespace std;

const int N = 1e5 + ;
const int M = 1e5 + ;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 +;

int n, t[N], dp[N][], mn[N], a[N];
int st1[N], st2[N], head1, head2, rear1, rear2;

int main() {
    memset(dp, inf, sizeof(dp));
    memset(mn, inf, sizeof(mn));
    mn[] = ;
    scanf("%d", &n);
    for(int i = ; i <= n; i++) {
        scanf("%d", &t[i]);
    }

    dp[][] = ;
    dp[][] = ;
    dp[][] = ;

    st1[rear1++] = ;
    st2[rear2++] = ;

    for(int i = ; i <= n; i++) {
        for(int j = ; j < ; j++) mn[i - ] = min(mn[i - ], dp[i - ][j]);
        dp[i][] = mn[i - ] + ;
        dp[i][] = mn[i - ] + ;
        dp[i][] = mn[i - ] + ;
        while(head1 < rear1 && t[i] - t[st1[head1]] >= ) head1++;
        while(head2 < rear2 && t[i] - t[st2[head2]] >= ) head2++;

        if(head1 < rear1) dp[i][] = min(dp[i][], dp[st1[head1]][]);
        if(head2 < rear2) dp[i][] = min(dp[i][], dp[st2[head2]][]);

        while(head1 < rear1 && dp[i][] < dp[st1[rear1 - ]][]) rear1--;
        while(head2 < rear2 && dp[i][] < dp[st2[rear2 - ]][]) rear2--;

        st1[rear1++] = i;
        st2[rear2++] = i;
    }

    for(int j = ; j < ; j++) {
        mn[n] = min(mn[n], dp[n][j]);
    }

    for(int i = ; i <= n; i++) {
        printf("%d\n", mn[i] - mn[i - ]);
    }
    return ;
}
/*
*/