DFS + 剪枝 PKU 1088

标签：dfs   剪枝   

Description

 1  2  3  4 5

16 17 18 19 6

15 24 25 20 7

14 23 22 21 8

13 12 11 10 9

Input

Output

Sample Input

5 5
1 2 3 4 5
16 17 18 19 6
15 24 25 20 7
14 23 22 21 8
13 12 11 10 9

Sample Output

25

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <math.h>
#include <algorithm>
#include <iostream>
using namespace std;
#define MAXN 111
int num[MAXN][MAXN];
int ans[MAXN][MAXN];
int n,m;
int xx[4] = {-1,0,1,0};
int yy[4] = {0,1,0,-1};

int DFS(int x,int y){
    if(ans[x][y] > 1){//如果这个点已经搜索过了就直接返回，不然会超时
        return ans[x][y];
    }
    int i;
    for(i=0;i<4;i++){
        int dx = x + xx[i];
        int dy = y + yy[i];
        if(dx>=0 && dy<n && dy>=0 && dy<m && num[dx][dy]<num[x][y]){
            int mmax = DFS(dx,dy);
            if(ans[x][y] < mmax+1){
                ans[x][y] = mmax+1;//改点能取到的最大值
            }
        }
    }

    return ans[x][y];
}

int main(){
    int i,j;

    while(~scanf("%d%d",&n,&m)){
        for(i=0;i<n;i++){
            for(j=0;j<m;j++){
                scanf("%d",&num[i][j]);
                ans[i][j] = 1;
            }
        }
        int sum = -1;
        for(i=0;i<n;i++){
            for(j=0;j<m;j++){
                int mark = DFS(i,j);
                if(ans[i][j] > sum){
                    sum = ans[i][j];
                }
            }
        }
        printf("%d\n",sum);
    }
}

DFS + 剪枝 PKU 1088

标签：dfs   剪枝   

原文地址：http://blog.csdn.net/zcr_7/article/details/41704439