10067 - Playing with Wheels
题目页：https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1008
从一开始思路就不对，之后才焕然大悟……每次都是这样。
还有，感觉搜索和图遍历有点分不清呢。
在第63行加入
1 if (u == target) 2 return;
可以提速很多，可以从300ms左右降低到100ms以内。
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#include <iostream>#include <queue>#define Dec true#define Inc falseint start; // 开始数值int target; // 目标数值bool op[4]; // 4 个转盘的操作int ban_number; // 禁止数的个数int ban[10001]; // 记录禁止数的数组struct{ int parent; bool used;} buffer[10001]; // 顶点// 增大数值void decrease(int current[], int i){ current[i]--; if (current[i] == -1) current[i] = 9;}// 减小数值void increase(int current[], int i){ current[i]++; if (current[i] == 10) current[i] = 0;}// 广度优先搜索void bfs(){ std::queue<int> q; // 初始化顶点 for (int i = 0; i < 10000; i++) { buffer[i].parent = -1; buffer[i].used = false; } // 把禁止数标记为已发现 for (int i = 0; i < ban_number; i++) { buffer[ban[i]].used = true; } // 初始化开始节点 buffer[start].used = true; q.push(start); while(!q.empty()) { int u = q.front(); q.pop(); int depart[4]; int a = u / 1000; int b = (u - a*1000) / 100; int c = (u - a*1000 - b *100) / 10; int d = (u - a*1000 - b *100 - c *10); depart[0] = a; depart[1] = b; depart[2] = c; depart[3] = d; for (int i = 0; i < 4; i++) { decrease(depart, i); { int x = depart[0] * 1000 + depart[1] * 100 + depart[2] * 10 + depart[3]; if (buffer[x].used == false) { buffer[x].parent = u; buffer[x].used = true; q.push(x); } } increase(depart, i); increase(depart, i); { int x = depart[0] * 1000 + depart[1] * 100 + depart[2] * 10 + depart[3]; if (buffer[x].used == false) { buffer[x].parent = u; buffer[x].used = true; q.push(x); } } decrease(depart, i); } }}// 读取四个个位数组成一个四位数，并返回这个四位数int read4(){ int a, b, c, d; scanf("%d%d%d%d", &a, &b, &c, &d); return a * 1000 + b *100 + c * 10 + d;}// mainint main(){ int n; scanf("%d", &n); for (int i = 0; i < n; i++) { start = read4(); target = read4(); scanf("%d", &ban_number); for (int j = 0; j < ban_number; j++) { ban[j] = read4(); } bfs(); { int x = target; int steps = 0; while(x != -1 && x != start) { steps++; x = buffer[x].parent; } if (x == start) printf("%d
", steps); else printf("-1
"); } } return 0;} |