Samsung-Rock Climbing

#include <iostream>

using namespace std;

// Input:
// 5 8
// ____   G
//       _
//      __
//       __
// ________

// 5 8
// ____   G

//      __
//       _
// ________

// Output:
// 3
// 4

int n, m, level, flag;
int A[100][100];
int vis[100][100];
int x;
int minh;

void dfs(int x, int y){
    vis[x][y] = 1;
    if(A[x][y] == 2){
        flag = 1;
        return;
    }
    if(y-1 >= 0 && !vis[x][y-1] && A[x][y-1])
        dfs(x, y-1);
    if(y+1 < m && !vis[x][y+1] && A[x][y+1])
        dfs(x, y+1);
    int h = 1;
    while(h <= level && x+h < n){
        if(A[x+h][y] && !vis[x+h][y])
            dfs(x+h, y);
        h++;
    }
    h = 1;
    while(h <= level && x-h >= 0){
        if(A[x-h][y] && !vis[x-h][y])
            dfs(x-h, y);
        h++;
    }
}

void solve(){
    int h = n-1, l = 0;
    minh = n;
    while(1){
        if(l > h)
            return;
        flag = 0;
        level = (h+l)/2;
        for(int i=0; i<n; ++i)
            for(int j=0; j<m; ++j)
                vis[i][j] = 0;
        dfs(n-1, 0);
        if(!flag){
            if(level == n-1)
                return;
            l = level+1;
        }
        else{
            minh = min(minh, level);
            if(!level)
                return;
            h = level-1;
        }
    }
}

int main() {
    cin>>n>>m;
    char x[m+1];
    cin.getline(x, sizeof(x));
    for(int i=0; i<n; ++i){
        cin.getline(x, sizeof(x));
        for(int j=0; j<m; ++j){
            if(x[j] == ' ')
                A[i][j] = 0;
            else if(x[j] == '_')
                A[i][j] = 1;
            else if(x[j] == 'G')
                A[i][j] = 2;
        }
    }
    solve();
    cout<<((minh != n)? minh: -1);
    return 0;
}