hdu 4267 A Simple Problem with Integers
2013-05-02 19:20
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A Simple Problem with Integers
Time Limit: 5000/1500 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2178 Accepted Submission(s): 709
Problem Description
Let A1, A2, ... , AN be N elements. You need to deal with two kinds of operations. One type of operation is to add a given number to a few numbers in a given interval. The other is to query the value of some element.
Input
There are a lot of test cases.
The first line contains an integer N. (1 <= N <= 50000)
The second line contains N numbers which are the initial values of A1, A2, ... , AN. (-10,000,000 <= the initial value of Ai <= 10,000,000)
The third line contains an integer Q. (1 <= Q <= 50000)
Each of the following Q lines represents an operation.
"1 a b k c" means adding c to each of Ai which satisfies a <= i <= b and (i - a) % k == 0. (1 <= a <= b <= N, 1 <= k <= 10, -1,000 <= c <= 1,000)
"2 a" means querying the value of Aa. (1 <= a <= N)
Output
For each test case, output several lines to answer all query operations.
Sample Input
4
1 1 1 1
14
2 1
2 2
2 3
2 4
1 2 3 1 2
2 1
2 2
2 3
2 4
1 1 4 2 1
2 1
2 2
2 3
2 4
Sample Output
1
1
1
1
1
3
3
1
2
3
4
1
题意:
应该很简单了,自行解决吧
解析:
这题因为数据规模是50000,所以说要是最坏的情况的话,即a=1,b=50000,k=1时间规模就是50000*50000,肯定超时(当然竞赛的时候也可以直接编试试人品,说不定这就是个水题,直接过了呢,事实上我试了,的确过不了啊,超时),然后查了解题报告之后才发现可以用树状数组来求。
关于树状数组的话,结合我前面的结题报告poj 3067 japan这一题的话,其实也挺好求的。主要思路就是:把2需要输出的结果分成两部分,一部分是原有的,一部分是修改的,输出的时候就是原有的加上修改的就行了。而这里面修改的部分就可以用树状数组来模拟了。
树状数组分成两种:一种是修改点来求区间的和,如poj 3067 japan,另一种就是对区间做出修改来求点的值,但是这一种只能修改区间上连续的点,而这一题是隔k的值修改,所以就很巧妙的把对于取余k相同的点全都存在另一个数组里。对于这两种来说的话,第一种是向上修改,向下统计,第二种是向下修改,向上统计(这是为什么我还没搞懂,但是先这么记着吧,详见大牛网址http://blog.csdn.net/shahdza/article/details/6314818)
#include<stdio.h> #include<string.h> #define Max 50001 int n,num[Max]; int node[11][11][Max];//第一个存k的值,第二个存num数组下标取余k的值,第三个就是树状数组了 int lowbit(int x) { return x&(-x); } void update(int border,int k,int c,int mod) { for(int i = border ; i > 0;i -= lowbit(i))//向下修改 node[k][mod][i] += c; } int getvalue(int x) { int ans = 0; for(int k = 1 ; k <= 10 ; k ++)//假如2的前面已经进行了多次1操作且k不同的话,就需要枚举所有的k的值都加一遍 { int mod = x % k; for(int j = x ; j <= n; j += lowbit(j))//向上统计 ans += node[k][mod][j]; } return ans; } int main() { while(scanf("%d",&n) != EOF) { memset(num,0,sizeof(num)); memset(node,0,sizeof(node)); for(int i = 1; i <= n ; i ++)//经验表明,从1开始最好 scanf("%d",&num[i]); int op,count; scanf("%d",&count); while(count--) { scanf("%d",&op); if(op == 1) { int a,b,k,c; scanf("%d%d%d%d",&a,&b,&k,&c); update(b,k,c,a%k); //把从1到b所有的都+c update(a-1,k,-c,a%k); //把从1到a所有的都-c,相当于从a到b的加c } else { int x; scanf("%d",&x); int sum = getvalue(x); printf("%d\n",sum + num[x]);//把原有值和增加量加在一起 } } } return 0; }
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