【POJ】2823 Sliding Window

单调队列。

  1 /* 2823 */
  2 #include <iostream>
  3 #include <sstream>
  4 #include <string>
  5 #include <map>
  6 #include <queue>
  7 #include <set>
  8 #include <stack>
  9 #include <vector>
 10 #include <deque>
 11 #include <algorithm>
 12 #include <cstdio>
 13 #include <cmath>
 14 #include <ctime>
 15 #include <cstring>
 16 #include <climits>
 17 #include <cctype>
 18 #include <cassert>
 19 #include <functional>
 20 #include <iterator>
 21 #include <iomanip>
 22 using namespace std;
 23 //#pragma comment(linker,"/STACK:102400000,1024000")
 24
 25 #define sti                set<int>
 26 #define stpii            set<pair<int, int> >
 27 #define mpii            map<int,int>
 28 #define vi                vector<int>
 29 #define pii                pair<int,int>
 30 #define vpii            vector<pair<int,int> >
 31 #define rep(i, a, n)     for (int i=a;i<n;++i)
 32 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 33 #define clr                clear
 34 #define pb                 push_back
 35 #define mp                 make_pair
 36 #define fir                first
 37 #define sec                second
 38 #define all(x)             (x).begin(),(x).end()
 39 #define SZ(x)             ((int)(x).size())
 40 #define lson            l, mid, rt<<1
 41 #define rson            mid+1, r, rt<<1|1
 42
 43 const int maxn = 1e6+5;
 44 int n, k;
 45 int a[maxn];
 46 int Q[maxn], P[maxn];
 47 int mn[maxn], mx[maxn];
 48
 49 void getMin() {
 50     int l = 1, r = 0;
 51     int i;
 52
 53     for (i=0; i<k-1; ++i) {
 54         while (l<=r && Q[r]>=a[i])
 55             --r;
 56         Q[++r] = a[i];
 57         P[r] = i;
 58     }
 59
 60     for (; i<n; ++i) {
 61         while (l<=r && Q[r]>=a[i])
 62             --r;
 63         Q[++r] = a[i];
 64         P[r] = i;
 65         while (P[l] < i-k+1)
 66             ++l;
 67         mn[i-k+1] = Q[l];
 68     }
 69 }
 70
 71 void getMax() {
 72     int l = 1, r = 0;
 73     int i;
 74
 75     for (i=0; i<k-1; ++i) {
 76         while (l<=r && Q[r]<=a[i])
 77             --r;
 78         Q[++r] = a[i];
 79         P[r] = i;
 80     }
 81
 82     for (; i<n; ++i) {
 83         while (l<=r && Q[r]<=a[i])
 84             --r;
 85         Q[++r] = a[i];
 86         P[r] = i;
 87         while (P[l] < i-k+1)
 88             ++l;
 89         mx[i-k+1] = Q[l];
 90     }
 91 }
 92
 93 void solve() {
 94     getMin();
 95     getMax();
 96     rep(i, 0, n-k+1) {
 97         if (i == n-k)
 98             printf("%d\n", mn[i]);
 99         else
100             printf("%d ", mn[i]);
101     }
102     rep(i, 0, n-k+1) {
103         if (i == n-k)
104             printf("%d\n", mx[i]);
105         else
106             printf("%d ", mx[i]);
107     }
108 }
109
110 int main() {
111     ios::sync_with_stdio(false);
112     #ifndef ONLINE_JUDGE
113         freopen("data.in", "r", stdin);
114         freopen("data.out", "w", stdout);
115     #endif
116
117     scanf("%d %d", &n, &k);
118     rep(i, 0, n)
119         scanf("%d", &a[i]);
120     solve();
121
122     #ifndef ONLINE_JUDGE
123         printf("time = %d.\n", (int)clock());
124     #endif
125
126     return 0;
127 }