USACO Section 1.4 Mother's Milk 搜索-优快云博客

这道题是一个让人做完觉得很爽的搜索题，可以用深搜也可以用宽搜。相对来说，深搜的代码量稍微小一点。搜索策略就是模拟倒来倒去的过程，并且出现重复的没有意义。

BFS版本：我是人工写了个队列，这样比STL中的快一点/* ID: sdj22251 PROG: calfflac LANG: C++ */ #include <iostream> #include <vector> #include <list> #include <map> #include <set> #include <deque> #include <queue> #include <stack> #include <bitset> #include <algorithm> #include <functional> #include <numeric> #include <utility> #include <sstream> #include <iomanip> #include <cstdio> #include <cmath> #include <cstdlib> #include <cctype> #include <string> #include <cstring> #include <cmath> #include <ctime> #define MAX 2000000000 #define LOCA #define M 1007 using namespace std; int a, b, c; bool can[M]; bool flag[M][M]; struct wwj { int x, y, z; wwj(){} wwj(int xx, int yy, int zz) { x = xx; y = yy; z = zz; } }q[M * M]; void bfs(int x, int y, int z) { int head = 0, tail = 0; wwj A(x, y, z); q[tail++] = A; flag[x][y] = true; if(A.x == 0) can[A.z] = true; while(head < tail) { A = q[head++]; if(A.x == 0) can[A.z] = true; if(A.x < a && A.z > 0) { if(A.z > a - A.x && !flag[a][A.y]) {wwj B(a, A.y, A.z - a + A.x); flag[B.x][B.y] = true; q[tail++] = B;} if(A.z <= a - A.x && !flag[A.x + A.z][A.y]) {wwj B(A.x + A.z, A.y, 0); flag[B.x][B.y] = true; q[tail++] = B;} } if(A.y < b && A.x > 0) { if(A.x > b - A.y && !flag[A.x + A.y - b][b]) {wwj B(A.x + A.y - b, b, A.z); flag[B.x][B.y] = true; q[tail++] = B;} if(A.x <= b - A.y && !flag[0][A.x + A.y]) {wwj B(0, A.x + A.y, A.z); flag[B.x][B.y] = true; q[tail++] = B;} } if(A.z < c && A.y > 0) { if(A.y > c - A.z && !flag[A.x][A.y + A.z - c]) {wwj B(A.x, A.y + A.z - c, c); flag[B.x][B.y] = true; q[tail++] = B;} if(A.y <= c - A.z && !flag[A.x][0]) {wwj B(A.x, 0, A.z + A.y); flag[B.x][B.y] = true; q[tail++] = B;} } if(A.x > 0 && A.z < c) { if(A.x > c - A.z && !flag[A.x + A.z - c][A.y]) {wwj B(A.x + A.z - c, A.y, c);flag[B.x][B.y] = true; q[tail++] = B;} if(A.x <= c - A.z && !flag[0][A.y]) {wwj B(0, A.y, A.z + A.x);flag[B.x][B.y] = true; q[tail++] = B;} } if(A.y > 0 && A.x < a) { if(A.y > a - A.x && !flag[a][A.y + A.x - a]) {wwj B(a, A.y + A.x - a, A.z);flag[B.x][B.y] = true; q[tail++] = B;} if(A.y <= a - A.x && !flag[A.x + A.y][0]) {wwj B(A.x + A.y, 0, A.z);flag[B.x][B.y] = true; q[tail++] = B;} } if(A.z > 0 && A.y < b) { if(A.z > b - A.y && !flag[A.x][b]) {wwj B(A.x, b, A.z + A.y - b);flag[B.x][B.y] = true; q[tail++] = B;} if(A.z <= b - A.y && !flag[A.x][A.y + A.z]) {wwj B(A.x, A.y + A.z, 0);flag[B.x][B.y] = true; q[tail++] = B;} } } } int main() { #ifdef LOCAL freopen("calfflac.in","r",stdin); freopen("calfflac.out","w",stdout); #endif int i; scanf("%d%d%d", &a, &b, &c); bfs(0, 0, c); for(i = 0; i <= c; i++) if(can[i]) printf("%d ", i); printf("\n"); return 0; }DFS版本：可以看到，步骤都很明确

/* ID: sdj22251 PROG: calfflac LANG: C++ */ #include <iostream> #include <vector> #include <list> #include <map> #include <set> #include <deque> #include <queue> #include <stack> #include <bitset> #include <algorithm> #include <functional> #include <numeric> #include <utility> #include <sstream> #include <iomanip> #include <cstdio> #include <cmath> #include <cstdlib> #include <cctype> #include <string> #include <cstring> #include <cmath> #include <ctime> #define MAX 2000000000 #define LOCA #define M 1007 using namespace std; int a, b, c; bool can[M]; bool flag[M][M]; void dfs(int x, int y, int z) { if(flag[x][y]) return; flag[x][y] = true; if(x == 0) can[z] = true; if(x < a && z > 0) { if(z > a - x) dfs(a, y, z - a + x); if(z <= a - x) dfs(x + z, y, 0); } if(y < b && x > 0) { if(x > b - y) dfs(x + y - b, b, z); if(x <= b - y) dfs(0, x + y, z); } if(z < c && y > 0) { if(y > c - z) dfs(x, y + z - c, c); if(y <= c - z) dfs(x, 0, z + y); } if(x > 0 && z < c) { if(x > c - z) dfs(x + z - c, y, c); if(x <= c - z) dfs(0, y, z + x); } if(y > 0 && x < a) { if(y > a - x) dfs(a, y + x - a, z); if(y <= a - x) dfs(x + y, 0, z); } if(z > 0 && y < b) { if(z > b - y) dfs(x, b, z + y - b); if(z <= b - y) dfs(x, y + z, 0); } } int main() { #ifdef LOCAL freopen("calfflac.in","r",stdin); freopen("calfflac.out","w",stdout); #endif int i; scanf("%d%d%d", &a, &b, &c); dfs(0, 0, c); for(i = 0; i <= c; i++) if(can[i]) printf("%d ", i); printf("\n"); return 0; }