递推DP HDOJ 5092 Seam Carving

 /*
题意：从上到下，找最短路径，并输出路径
DP：类似数塔问题，上一行的三个方向更新dp，路径输出是关键
*/
#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <ctime>
#include <cstdlib>
using namespace std;

const int MAXN = 1e2 + 10;
const int INF = 0x3f3f3f3f;
int a[MAXN][MAXN];
int dp[MAXN][MAXN];
int pre[MAXN][MAXN];

void print(int x, int y)
{
if (x == 1)
{
printf ("%d", y);    return ;
}
print (x - 1, pre[x][y]);
printf (" %d", y);
}

int main(void)        //HDOJ 5092 Seam Carving
{
//freopen ("C.in", "r", stdin);

int n, m, t, cas = 0;
scanf ("%d", &t);
while (t--)
{
scanf ("%d%d", &n, &m);
for (int i=1; i<=n; ++i)
for (int j=1; j<=m; ++j)    scanf ("%d", &a[i][j]);
memset (pre, 0, sizeof (pre));

for (int i=2; i<=n; ++i)
for (int j=1; j<=m; ++j)    dp[i][j] = INF;
for (int i=1; i<=m; ++i)    dp[1][i] = a[1][i];

for (int i=2; i<=n; ++i)
{
for (int j=m; j>=1; --j)
{
for (int k=1; k>=-1; --k)
{
if (j + k < 1 || j + k > m)    continue;
if (dp[i][j] > dp[i-1][j+k] + a[i][j])
{
dp[i][j] = dp[i-1][j+k] + a[i][j];
pre[i][j] = j + k;
}
}
}
}

int k = m;    int mn = dp
[m];
for (int i=m-1; i>=1; --i)
{
if (mn > dp
[i])    {mn = dp
[i];    k = i;}
}

printf ("Case %d\n", ++cas);
print (n, k);
puts ("");
}

return 0;
}

/*
Case 1
2 1 1 2
Case 2
3 2 1 1 2 1
*/