USACO Section 1.4 Mother's Milk 搜索

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: sdj22251PROG: calfflacLANG: 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 1007using 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: sdj22251PROG: calfflacLANG: 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 1007using 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;}