集训第五周动态规划 F题 最大子矩阵和
2015-08-12 20:03
323 查看
Given a two-dimensional array of positive and negative integers, a sub-rectangle is any contiguous sub-array of size 1*1 or greater located within the whole array. The sum of a rectangle is the sum of all the elements in that rectangle. In this problem the sub-rectangle with the largest sum is referred to as the maximal sub-rectangle.
As an example, the maximal sub-rectangle of the array:
0 -2 -7 0
9 2 -6 2
-4 1 -4 1
-1 8 0 -2
is in the lower left corner:
9 2
-4 1
-1 8
and has a sum of 15.
Input
The input consists of an N * N array of integers. The input begins with a single positive integer N on a line by itself, indicating the size of the square two-dimensional array. This is followed by N^2 integers separated by whitespace (spaces and newlines). These are the N^2 integers of the array, presented in row-major order. That is, all numbers in the first row, left to right, then all numbers in the second row, left to right, etc. N may be as large as 100. The numbers in the array will be in the range [-127,127].
Output
Output the sum of the maximal sub-rectangle.
Sample Input
Sample Output
As an example, the maximal sub-rectangle of the array:
0 -2 -7 0
9 2 -6 2
-4 1 -4 1
-1 8 0 -2
is in the lower left corner:
9 2
-4 1
-1 8
and has a sum of 15.
Input
The input consists of an N * N array of integers. The input begins with a single positive integer N on a line by itself, indicating the size of the square two-dimensional array. This is followed by N^2 integers separated by whitespace (spaces and newlines). These are the N^2 integers of the array, presented in row-major order. That is, all numbers in the first row, left to right, then all numbers in the second row, left to right, etc. N may be as large as 100. The numbers in the array will be in the range [-127,127].
Output
Output the sum of the maximal sub-rectangle.
Sample Input
4 0 -2 -7 0 9 2 -6 2 -4 1 -4 1 -1 8 0 -2
Sample Output
15 这道题其实就是求最大子段和,需要把原题数据变化一下,例如 0 -2 -7 0 9 2 -6 2 -4 1 -4 1 -1 8 0 -2 这个矩阵我选择的是 9 2 -4 1 -1 8 那么我还可以把这个选择过程看待为求数组 4 11 -10 1 的最大子段和,很显然是选择4 11,答案为15 那么4 11 -10 1是怎么来的呢,是我把2 3 4行数组组合成一个数组得来的 那么这道题的解法就出来了,不断枚举行区间,得到一个新数组,然后求最大子段和
#include"iostream" #include"cstring" using namespace std; const int maxn=110; int b[maxn],a[maxn][maxn]; int n; void Init() { int t; memset(a,0,sizeof(a)); for(int i=1;i<=n;i++) { for(int j=1;j<=n;j++) { cin>>t; a[i][j]=a[i-1][j]+t; } } } int main() { while(cin>>n) { Init(); int sum,ans,temp; sum=0; ans=-1000000000; int c=1; for(int i=1;i<=n;i++) for(int j=i;j<=n;j++) { sum=0; for(int k=1;k<=n;k++) { temp=a[j][k]-a[i-1][k]; sum+=temp; if(sum>ans) { ans=sum; } if(sum<0) { sum=0; } } } cout<<ans<<endl; } return 0; }
相关文章推荐
- 1 ubuntu下装setuptools
- Hdu3363 贪心
- HDOJ 1162 Eddy's picture(最小生成树prim算法)
- 【POJ 1837】 Balance
- CS224d lecture 14札记
- [知识点]树状数组(附逆序对)
- 肥胖也是一种病 胖起来也挺“要命”
- 提升vs2013、vs2015管理员权限win8.1
- POJ2002---Squares(找正方形的个数)
- 最长公共子序列
- nyoj187 快速查找素数
- twisted08-1 多级访问-httpserver
- 机器视觉开源代码集合(转载)
- Hdu1009 贪心
- Implementation Notes: Runtime Environment Map Filtering for Image Based Lighting
- Makefile
- C#中的委托和事件
- hdu 2063 过山车 二分图+最大匹配+匈牙利算法
- hdu 2732 && poj 2711 Leapin' Lizards(dinic && 拆点建图经典)
- Solr(5.2.1)安装、启动和建立索引