[HDOJ5092] Seam Carving（DP，记录路径）

题目链接：https://vjudge.net/problem/HDU-5092

很简单的DP，记录路径的方法也很基础。有一个小小的坑点就是希望输出最靠右的最大结果。

那么在更新的时候，尽可能向右走，并且输出结果的时候，从右到左扫描即可。

#include <bits/stdc++.h>
using namespace std;

const int maxn = 110;
int f[maxn][maxn];
int path[maxn][maxn];
int a[maxn][maxn];
int n, m;

int main() {
    // freopen("in", "r", stdin);
    int T, _ = 1;
    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(f, 0x7f, sizeof(f));
        memset(path, -1, sizeof(path));
        for(int i = 1; i <= n; i++) f[1][i] = a[1][i];
        for(int i = 2; i <= n; i++) {
            for(int j = m; j >= 1; j--) {
                if(f[i][j] > f[i-1][j-1] + a[i][j]) {
                    path[i][j] = 0;
                    f[i][j] = f[i-1][j-1] + a[i][j];
                }
                if(f[i][j] >= f[i-1][j] + a[i][j]) {
                    path[i][j] = 1;
                    f[i][j] = f[i-1][j] + a[i][j];
                }
                if(f[i][j] >= f[i-1][j+1] + a[i][j]) {
                    path[i][j] = 2;
                    f[i][j] = f[i-1][j+1] + a[i][j];
                }
            }
        }
        int ret = 0x7f7f7f7f, id = -1;
        for(int i = m; i >= 1; i--) {
            if(ret > f[n][i]) {
                ret = f[n][i];
                id = i;
            }
        }
        stack<int> st;
        st.push(id);
        int y = id;
        for(int i = n; i >= 2; i--) {
            if(path[i][y] == 0) {
                y--;
            }
            else if(path[i][y] == 2) {
                y++;
            }
            st.push(y);
        }
        printf("Case %d
", _++);
        printf("%d", st.top()); st.pop();
        while(!st.empty()) {
            printf(" %d", st.top());
            st.pop();
        }
        printf("
");
    }
    return 0;
}