USACO算法系列——Big Barn

   题目：http://www.nocow.cn/index.php/Translate:USACO/bigbrn

   计算最大的正方形块。area[i][j]:表示以i,j为右下角的正方形的宽度。则

   area[i][j] = min(area[i-1][j],area[i][j-1],area[i-1][j-1])+1.

   代码如下：

#include <iostream>#include<fstream>#define SIZE 1001using namespace std;int map[SIZE][SIZE] = {0};int rmap[SIZE][SIZE] = {0};int n;int t;int result = 0;ifstream fin("bigbrn.in");ofstream fout("bigbrn.out");void read(){fin >> n >> t;int x, y;for (int i=0; i < t; i ++){fin >> x >> y;map[x][y] = -1;}}int issquare(int x, int y){if (x <= 1 || y <= 1){return 1;}else{int small = SIZE;if (rmap[x-1][y] < small){small = rmap[x-1][y];}if (rmap[x][y-1] < small){small = rmap[x][y-1];}if (rmap[x-1][y-1] < small){small = rmap[x-1][y-1];}return small + 1;}}void bigbrn(){for (int i=1; i <= n; i ++){for (int j=1; j <= n; j ++){if (map[i][j] >= 0){rmap[i][j] = issquare(i, j);if (result < rmap[i][j]){result = rmap[i][j];}//end if result}//end if map[i][j]}//end for j}//end for i}int main(){read();bigbrn();fout<<result << endl;}

    运行结果如下：

Executing... Test 1: TEST OK [0.000 secs, 10848 KB] Test 2: TEST OK [0.000 secs, 10848 KB] Test 3: TEST OK [0.000 secs, 10848 KB] Test 4: TEST OK [0.000 secs, 10848 KB] Test 5: TEST OK [0.000 secs, 10848 KB] Test 6: TEST OK [0.000 secs, 10848 KB] Test 7: TEST OK [0.000 secs, 10848 KB] Test 8: TEST OK [0.000 secs, 10848 KB] Test 9: TEST OK [0.000 secs, 10848 KB] Test 10: TEST OK [0.027 secs, 10848 KB] Test 11: TEST OK [0.027 secs, 10848 KB] Test 12: TEST OK [0.027 secs, 10848 KB] Test 13: TEST OK [0.027 secs, 10848 KB] Test 14: TEST OK [0.027 secs, 10848 KB] Test 15: TEST OK [0.027 secs, 10848 KB]All tests OK.YOUR PROGRAM ('bigbrn') WORKED FIRST TIME! That's fantastic-- and a rare thing. Please accept these special automatedcongratulations.

    有一个多月没有写博客了，主要是由于最近开题和写自然科学基金。然后做的很多事情也不被同学们理解。一直被别人嘲笑写算法，中间有段时间去做Code jam了。Google Code jam即将开赛，我也要努力学习，争取取得一点成绩啊。

    还有我的英语实在太烂了。明天还得努力。不管怎么样，先把USACO做完吧！还差11题。