luogu P1514 引水入城

搜索+dp

// luogu-judger-enable-o2
#include<cstdio>
#include<cstring>
#include<algorithm> 
const int maxn = 607;
int n,m; 
int map[maxn][maxn];  
int fs[5] = {1,0,-1,0,1};
bool vis[maxn];  
int l[maxn],r[maxn],dp[maxn]; 
bool V[maxn][maxn];  
void dfs(int x,int y,int root)  { 
    V[x][y] = 1; 
    if(x == n) { 
        vis[y] = 1; 
        l[root] = std::min (l[root],y);  r[root] = std::max (r[root],y); 
    } 
    for(int i = 0;i < 4;++ i) {
        int tx = x + fs[i],ty = y + fs[i + 1]; 
        if(!V[tx][ty] && tx >= 1 && tx <= n && ty >= 1 && ty <= m && map[tx][ty] < map[x][y]) dfs(tx,ty,root);
    } 

}
int main() { 
    scanf("%d%d",&n,&m) ; 
    memset(l,0x3f,sizeof l);
    for(int i = 1;i <= n;++ i) 
        for(int j = 1;j <= m;++ j) scanf("%d",&map[i][j]) ;
    for(int i = 1;i <= m; ++ i) {
        dfs(1,i,i); memset(V,0,sizeof V);  
    } int num = 0 ;
    for(int i = 1;i <= m;++ i) {
        if(!vis[i]) num ++ ;
    }
    if(num) {puts("0"); printf("%d
",num);return 0;}
    memset(dp,0x3f,sizeof dp);
    dp[0] = 0;
    for(int i = 1;i <= m; ++i) 
        	for (int j = 1;j <= r[i];j ++) 
            		dp[j] = std::min(dp[j],dp[l[i] - 1] + 1); 
    puts("1"); 
    printf("%d
",dp[m]); 
    return 0; 
}