标签：code mil class output where put ott nbsp 输入
描述
Given an N*N matrix, find the coolest square sub-matrix.
We define the cool value of the square matrix as X-Y where X indicating the sum of all integers of the main diagonal and Y indicating the sum of the other diagonal.
输入
The first line has a positive integer N (2 ≤ N ≤ 400), the size of the matrix.
The following N lines each contain N integers in the range [-1000, 1000], the elements of the matrix.
输出
Output the coolest value of a square sub-matrix.
样例输入
2
1 -2
4 5
样例输出
4
题意：
在n*n的矩阵中找到一个子矩阵，使得其 (正对角线整数之和-反对角线整数之和) 最大。
思路：
记录矩阵中各对角线的前缀和，将所取对角线两端的前缀和相减，所得即为该对角线整数之和。
#include<bits/stdc++.h> #define MAX 405 using namespace std; int A1[MAX][MAX],A2[MAX][MAX];//A1正对角线前缀和 与 A2反对角线前缀和 int main() { int i,j,k,n,x,maxx=-1; cin>>n; for(i=1;i<=n;i++) { for(j=1;j<=n;j++) { scanf("%d",&x); A1[i][j]=A1[i-1][j-1]+x;//左上加到右下 A2[i][j]=A2[i-1][j+1]+x;//右上加到左下 } } for(i=1;i<=n;i++) //起始行位置i for(j=1;j<=n;j++)//起始列位置j for(k=1;k<=min(n+1-i,n+1-j);k++)//小矩阵边长k maxx=max(maxx,A1[i+k][j+k]-A1[i-1][j-1]-(A2[i+k][j]-A2[i-1][j+k+1])); cout<<maxx<<endl; return 0; }
【TOJ 4475】The Coolest Sub-matrix（对角线前缀和）
标签：code mil class output where put ott nbsp 输入
原文地址：https://www.cnblogs.com/kannyi/p/9610277.html
