洛谷P2032题解

入门题。

仔细浏览题面，发现是滑动窗口的超级弱化版。

只需要搞一个单调队列维护最大值就可以了。

  1 #include<stdio.h>
  2 #define reg register
  3 #define ri reg int
  4 #define rep(i, x, y) for(ri i = x; i <= y; ++i)
  5 #define nrep(i, x, y) for(ri i = x; i >= y; --i)
  6 #define DEBUG 1
  7 #define ll long long
  8 #define max(i, j) (i) > (j) ? (i) : (j)
  9 #define min(i, j) (i) < (j) ? (i) : (j)
 10 #define read(i) io.READ(i)
 11 #define print(i) io.WRITE(i)
 12 #define push(i) io.PUSH(i)
 13 struct IO {
 14     #define MAXSIZE (1 << 20)
 15     #define isdigit(x) (x >= '0' && x <= '9')
 16     char buf[MAXSIZE], *p1, *p2;
 17     char pbuf[MAXSIZE], *pp;
 18     #if DEBUG
 19     #else
 20         IO() : p1(buf), p2(buf), pp(pbuf) {}
 21         ~IO() {
 22             fwrite(pbuf, 1, pp - pbuf, stdout);
 23         }
 24     #endif
 25     inline char gc() {
 26         #if DEBUG
 27             return getchar();
 28         #endif
 29         if(p1 == p2)
 30             p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin);
 31         return p1 == p2 ? ' ' : *p1++;
 32     }
 33     inline bool blank(char ch) {
 34         return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t';
 35     }
 36     template <class T>
 37     inline void READ(T &x) {
 38         register double tmp = 1;
 39         register bool sign = 0;
 40         x = 0;
 41         register char ch = gc();
 42         for(; !isdigit(ch); ch = gc())
 43             if(ch == '-') sign = 1;
 44         for(; isdigit(ch); ch = gc())
 45             x = x * 10 + (ch - '0');
 46         if(ch == '.')
 47             for(ch = gc(); isdigit(ch); ch = gc())
 48                 tmp /= 10.0, x += tmp * (ch - '0');
 49         if(sign) x = -x;
 50     }
 51     inline void READ(char *s) {
 52         register char ch = gc();
 53         for(; blank(ch); ch = gc());
 54         for(; !blank(ch); ch = gc())
 55             *s++ = ch;
 56         *s = 0;
 57     }
 58     inline void READ(char &c) {
 59         for(c = gc(); blank(c); c = gc());
 60     }
 61     inline void PUSH(const char &c) {
 62         #if DEBUG
 63             putchar(c);
 64         #else
 65             if(pp - pbuf == MAXSIZE) {
 66                 fwrite(pbuf, 1, MAXSIZE, stdout);
 67                 pp = pbuf;
 68             }
 69             *pp++ = c;
 70         #endif
 71     }
 72     template <class T>
 73     inline void WRITE(T x) {
 74         if(x < 0) {
 75             x = -x;
 76             PUSH('-');
 77         }
 78         static T sta[35];
 79         T top = 0;
 80         do {
 81             sta[top++] = x % 10;
 82             x /= 10;
 83         }while(x);
 84         while(top)
 85             PUSH(sta[--top] + '0');
 86     }
 87     template <class T>
 88     inline void WRITE(T x, char lastChar) {
 89         WRITE(x);
 90         PUSH(lastChar);
 91     }
 92 } io;
 93 int n, k, q[1000010], a[1000010];
 94 void getmax() {
 95     ri head = 0, tail = 0;
 96     rep(i, 1, k - 1) {
 97         while(head <= tail && a[q[tail]] <= a[i]) --tail;
 98         q[++tail] = i;
 99     }
100     rep(i, k, n) {
101         while(head <= tail && a[q[tail]] <= a[i]) --tail;
102         q[++tail] = i;
103         while(q[head] <= i - k) ++head;
104         print(a[q[head]]);
105         puts("");
106     }
107 }
108 int main() {
109     read(n), read(k);
110     rep(i, 1, n) read(a[i]);
111     getmax();
112     return 0;
113 }
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posted @ 2021-02-18 12:45  1358id  阅读(41)  评论(0)  编辑  收藏  举报