本文主要是介绍UVA 196 POJ 1420 Spreadsheet （DFS），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
http://poj.org/problem?id=1420
http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=132
Spreadsheet
| Spreadsheet |
In 1979, Dan Bricklin and Bob Frankston wrote VisiCalc, the first spreadsheet application. It became a huge success and, at that time, was the killer application for the Apple II computers. Today, spreadsheets are found on most desktop computers.
The idea behind spreadsheets is very simple, though powerful. A spreadsheet consists of a table where each cell contains either a number or a formula. A formula can compute an expression that depends on the values of other cells. Text and graphics can be added for presentation purposes.
You are to write a very simple spreadsheet application. Your program should accept several spreadsheets. Each cell of the spreadsheet contains either a numeric value (integers only) or a formula, which only support sums. After having computed the values of all formulas, your program should output the resulting spreadsheet where all formulas have been replaced by their value.
Figure: Naming of the top left cells
Input
The first line of the input file contains the number of spreadsheets to follow. A spreadsheet starts with a line consisting of two integer numbers, separated by a space, giving the number of columns and rows. The following lines of the spreadsheet each contain a row. A row consists of the cells of that row, separated by a single space.
A cell consists either of a numeric integer value or of a formula. A formula starts with an equal sign (=). After that, one or more cell names follow, separated by plus signs (+). The value of such a formula is the sum of all values found in the referenced cells. These cells may again contain a formula. There are no spaces within a formula.
You may safely assume that there are no cyclic dependencies between cells. So each spreadsheet can be fully computed.
The name of a cell consists of one to three letters for the column followed by a number between 1 and 999 (including) for the row. The letters for the column form the following series: A, B, C, ..., Z, AA, AB, AC, ..., AZ, BA, ..., BZ, CA, ..., ZZ, AAA, AAB, ..., AAZ, ABA, ..., ABZ, ACA, ..., ZZZ. These letters correspond to the number from 1 to 18278. The top left cell has the name A1. See figure 1.
Output
The output of your program should have the same format as the input, except that the number of spreadsheets and the number of columns and rows are not repeated. Furthermore, all formulas should be replaced by their value.
Sample Input
1 4 3 10 34 37 =A1+B1+C1 40 17 34 =A2+B2+C2 =A1+A2 =B1+B2 =C1+C2 =D1+D2
Sample Output
10 34 37 81 40 17 34 91 50 51 71 172
模拟EXCEL的求和操作，注意有可能运算改格之后的单元格，所以这里用到DFS，已经有值的格子不必再搜，没有值的继续搜
数据范围虽然很大，但实际上开个1000×1000的数组就够了，POJ上100×100都能过，很多人说1000×18278的数组会RE，我对此只想表示呵呵，人云亦云，UVA上根本不限内存，我开了1000×20000的数组在UVA上获得了AC，不过POJ上肯定要MLE的，还有POJ上的数据好像太水了，我有漏洞的代码居然也过了
#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<algorithm>
#include<ctime>
#include<cctype>
#include<cmath>
#include<string>
#include<cstring>
#include<stack>
#include<queue>
#include<list>
#include<vector>
#include<map>
#include<set>
#define sqr(x) ((x)*(x))
#define LL long long
#define itn int
#define INF 0x3f3f3f3f
#define PI 3.1415926535897932384626
#define eps 1e-10
#define mmusing namespace std;typedef pair<int,int> PAIR;int n,m;
int MAP[1010][1010];
char s[100];
vector<PAIR> v[1010][1010];void save(int i,int j)
{int p=0;int x=0,y=0;v[i][j].clear();while (s[p]!='\0'){p++;while (isalpha(s[p])){x=x*26+s[p]-64;p++;}while (isdigit(s[p])){y=y*10+s[p]-48;p++;}//printf("x=%d y=%d\n",x,y);v[i][j].push_back(PAIR(y,x));x=y=0;}
}int dfs(int x,int y)
{if (MAP[x][y]!=-1) return MAP[x][y];int res=0;for (int i=0;i!=v[x][y].size();i++)res+=dfs(v[x][y][i].first,v[x][y][i].second);return res;
}int main()
{#ifndef ONLINE_JUDGEfreopen("/home/fcbruce/文档/code/t","r",stdin);// freopen("/home/fcbruce/文档/code/t1","w",stdout);#endif // ONLINE_JUDGEint tt;scanf("%d",&tt);while (tt--){scanf("%d%d",&m,&n);memset(MAP,-1,sizeof(MAP));for (int i=1;i<=n;i++){for (int j=1;j<=m;j++){scanf("%s",s);if (isdigit(s[0])){MAP[i][j]=atoi(s);}else{//puts(s);save(i,j);//puts("----------------------");}}}for (int i=1;i<=n;i++){for (int j=1;j<=m;j++){if (MAP[i][j]==-1){MAP[i][j]=dfs(i,j);}printf(j==m?"%d\n":"%d ",MAP[i][j]);}}}return 0;
}
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