【HDOJ】4932 Miaomiao's Geometry

递归检测。因为dis数组开的不够大，各种wa。写了个数据发生器，果断发现错误，改完就过了。

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <algorithm>

 using namespace std;

 #define MAXN 55

 int n;
 double a[MAXN], dis[MAXN*];
 char visit[MAXN]; // 0: false, 1: left, 2:right

 bool dfs(int x, double l) {
     if (x == n-)
         return true;
     if (x == ) {
         visit[x] = ;
         return dfs(x+, l);
     }
     if (visit[x-] == ) {
         if (a[x-]+l <= a[x]) {
             visit[x] = ;
             if ( dfs(x+, l) )
                 return true;
         } else if (a[x]+l <= a[x+]) {
             visit[x] = ;
             return dfs(x+, l);
         }
         return false;
     } else {
         if (a[x-]+*l <= a[x] || a[x-]+l==a[x]) {
             visit[x] = ;
             if ( dfs(x+, l) )
                 return true;
         } else if (a[x]+l <= a[x+]) {
             visit[x] = ;
             return dfs(x+, l);
         }
         return false;
     }
 }

 int main() {
     //FILE *fout = fopen("data", "w");
     int case_n, m;
     int i;

     scanf("%d", &case_n);
     while (case_n--) {
         scanf("%d", &n);
         for (i=; i<n; ++i)
             scanf("%lf", &a[i]);
         sort(a, a+n);
         for (m=, i=; i<n; ++i) {
             dis[m++] = a[i] - a[i-];
             dis[m++] = (a[i] - a[i-])/;
         }
         sort(dis, dis+m);
         dis[m] = 0.0f;
         for (i=m-; i>=; --i) {
             if (dis[i] != dis[i+]) {
                 memset(visit, , sizeof(visit));
                 if ( dfs(, dis[i]) )
                     break;
             }
         }
         printf("%.3lf\n", dis[i]);
         //fprintf(fout, "%.3lf\n", dis[i]);
     }

     return ;
 }