POJ 2823 Sliding Window

很CHUO的代码

用的是单调队列

还有更好的做法 以后补上

#include <stdio.h>

struct Queue{
    int idx, val;
}que[1000000];
int a[1000000];
int head, tail;

int main(){
    int n, k;
    scanf("%d%d",&n, &k);
    for(int i = 0; i < n; ++i){
        scanf("%d",&a[i]);
    }
    // k 为1时候的特殊情况， 还有更好的做法..
    if( k == 1 ){
        for(int i = 0; i < n; ++i){
            if( i )
                printf(" ");
            printf("%d",a[i]);
        }    
        printf("\n");
        for(int i = 0; i < n; ++i){
            if( i )
                printf(" ");
            printf("%d",a[i]);
        }    
        printf("\n");
        return 0;
    }
    head = tail = 0;
    que[tail].val = a[0];
    que[tail].idx = 0;
    bool first = true;
    for(int i = 1; i < n; ++i){
        
        while( head <= tail && que[tail].val > a[i] ){
            tail--;
        }
        tail++;
        que[tail].val = a[i];
        que[tail].idx = i;
        while( i - que[head].idx >= k ){
            head++;
        }
        if( i >= k - 1 ){
            if( first )
                first = false;
            else
                printf(" ");
            printf("%d",que[head].val);
        }
    }
    printf("\n");
    head = tail = 0;
    que[tail].val = a[0];
    que[tail].idx = 0;
    first = true;
    for(int i = 1; i < n; ++i){
        
        while( head <= tail && que[tail].val < a[i] ){
            tail--;
        }
        tail++;
        que[tail].val = a[i];
        que[tail].idx = i;
        if( i - que[head].idx >= k ){
            head++;
        }
        if( i >= k - 1 ){
            if( first )
                first = false;
            else
                printf(" ");
            printf("%d",que[head].val);
        }
        
    }
    printf("\n");
    return 0;
}