最近做课设时,找了网上好多关于关于这个问题的博客,但是都是只有最后的结果与建立的备忘表,都没有去标记到底哪个点是哪条路走过的,因此将对行走过点的标记过程写成了一个函数,具体的思想网上也写的很多,推荐几个
https://blog.youkuaiyun.com/greenhandcgl/article/details/51399222 | |
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这个解释的比较详细而且给出了另一种做法dfs,但是还未曾验证过:
https://blog.youkuaiyun.com/qq_40788630/article/details/89738232 | |
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这个就比较有意思了:
(https://blog.youkuaiyun.com/sevenmit/article/details/8959923)
下面是具体代码
可将注释去掉加以深理解
#include<iostream>
#include<algorithm>
#include<string>
//row 行 col 列
using namespace std;
const int MAX = 55;
int dp[2* MAX][MAX][MAX];//建表
int maze[MAX][MAX], n, m;//迷宫数组
int mark[MAX][MAX];//标记走过的路径
//千篇一律的代码,用来寻找宝藏并建表
void find_ans(int total, int row, int col) {
for (int l = 2; l<total; l++) {
for (int i = 1; i <= row; i++) {
for (int j = 1; j <= col; j++) {
if (i != j&&l >= i&&l >= j) {
dp[l][i][j] = max(max(dp[l - 1][i - 1][j], dp[l - 1][i][j - 1]), max(dp[l - 1][i - 1][j - 1], dp[l - 1][i][j])) + maze[i][l - i] + maze[j][l - j];
}
//cout << dp[l][i][j] << "\t";
}
//cout << endl;
}
//cout << endl;
}
dp[total][row][col] = max(dp[total - 1][row][row - 1], dp[total - 1][row - 1][row]) + maze[row][col];
printf_s("%d\n", dp[total][row][col]);
}
//标记走过的路径
void find_route(int k,int total,int row,int col) {
int max[3][1];
max[0][0] = row;//第一条路的行
max[1][0] = row;//第二条路的行
max[2][0] = dp[total][row][col];//待寻找的值
mark[row][col] = 3;
//printf_s("%d\n", max[2][0]);
for (int l = total; l > 2; l--) {
int r1 = maze[max[0][0]][l - max[0][0]];//第一条路径的回溯,此时该点宝藏的值
if (l == total) {
r1 = 0;
}
//cout <<"r1="<< r1 <<endl;
int r2 = maze[max[1][0]][l - max[1][0]];//第二条路径的回溯,此时该点宝藏的值
//cout << "r2=" << r2 << endl;
max[2][0] = max[2][0] - r1 - r2;//通过上一个的值减去一二条路径的值计算出下一个该查表的的数值
//cout << "testmax" << max[2][0]<<endl;
for (int i = 1; i <= row; i++) {
for (int j = i; j <=col; j++) {
if (dp[l-1][i][j] == max[2][0]) {
max[0][0] = i;//保存第一条路径此时经过的点
max[1][0] = j;//保存第二条路径此时经过的点
//cout <<"test"<< max[0][0] << "\t" << max[1][0] << endl;
break;
}
}
}
mark[max[0][0]][l-max[0][0]-1] = 1;//第一条路标记1
mark[max[1][0]][l-max[1][0]-1] = 2;//第二条路标记2
//cout << max[0][0] << "\t" << max[1][0] << "\t" << max[2][0] << endl;
}
//cout << endl;
}
int main() {
int c;
scanf_s("%d", &c);
int k = c;
while (k--) {
scanf_s("%d%d", &m, &n);
for (int i = 1; i <= m; i++) {
for (int j = 1; j <= n; j++) {
scanf_s("%d", &maze[i][j]);
}
}
if (n == 0 || m == 0) { printf("0\n"); continue; }
memset(dp, 0, sizeof(dp));
find_ans(n + m, m, n);
memset(mark, 0, sizeof(mark));
find_route(k, n + m, m, n);
mark[1][1] = 3;
for (int i = 1; i <= m; i++) {
for (int j = 1; j <= n; j++) {
cout << mark[i][j] << "\t";
}
cout << endl;
}
}
return 0;
}