6163 - Myth Busters

#include <iostream>#include<cstring>#include<cstdio>using namespace std; const int INF = 1 << 30; int a[4];int res[4];bool vis[4];bool flag;  int deal(int x,int y,int i)  //四则运算{    switch(i)    {    case 0 : return x + y;    case 1 : return x - y;    case 2 : return x * y;    case 3 : if(y != 0) return x / y;else return INF;    }} bool can()        //判断该种排列运用四则运算是否能算出{    int i,j,k;    int t1,t2,t3;    for(i = 0;i < 4;i ++)         //(a @ b) @ (c @ d)    {        t1 = deal(res[0],res[1],i);        if(t1 == INF) continue;        for(j = 0;j < 4;j ++)        {            t2 = deal(res[2],res[3],j);            if(t2 == INF) continue;            for(k = 0;k < 4;k ++)            {                t3 = deal(t1,t2,k);                if(t3 == 10) return 1;            }        }    }    for(i = 0;i < 4;i ++)     //((a @ b) @ c) @ d    {        t1 = deal(res[0],res[1],i);        if(t1 == INF) continue;        for(j = 0;j < 4;j ++)        {            t2 = deal(t1,res[2],j);            if(t2 == INF) continue;            for(k = 0;k < 4;k ++)            {                t3 = deal(t2,res[3],k);                if(t3 == 10) return 1;            }        }    }    for(i = 0;i < 4;i ++)     //(a @ (b @ c)) @ d    {        t1 = deal(res[1],res[2],i);        if(t1 == INF) continue;        for(j = 0;j < 4;j ++)        {            t2 = deal(res[0],t1,j);            if(t2 == INF) continue;            for(k = 0;k < 4;k ++)            {                t3 = deal(t2,res[3],k);                if(t3 ==10) return 1;            }        }    }    for(i = 0;i < 4;i ++)     //a @ (b @ (c @ d))    {        t1 = deal(res[2],res[3],i);        if(t1 == INF) continue;        for(j = 0;j < 4;j ++)        {            t2 = deal(res[1],t1,j);            if(t2 == INF) continue;            for(k = 0;k < 4;k ++)            {                t3 = deal(res[0],t2,k);                if(t3 == 10) return 1;            }        }    }    for(i = 0;i < 4;i ++)     //a @ ((b @ c) @ d)    {        t1 = deal(res[1],res[2],i);        if(t1 == INF) continue;        for(j = 0;j < 4;j ++)        {            t2 = deal(t1,res[3],j);            if(t2 == INF) continue;            for(k = 0;k < 4;k ++)            {                t3 = deal(res[0],t2,k);                if(t3 == 10) return 1;            }        }    }    return 0;    //都不能算出，说明无解} void dfs(int p)    //全排列{    if(p == 4)    {        if(can()) flag = 1;        return;    }    int i,j;    for(i = 0;i < 4;i ++)    {        if(!vis[i])         {            res[p] = a[i];            vis[i] = 1;            dfs(p + 1);            if(flag) return;            vis[i] = 0;        }    }} int main(){    char s[3];    int i,j,k;    int n;    while(cin>>n&&n)    {    int f=0;    while(n--)    {    cin>>s;    if(f)    continue;        for(i = 0;i < 4;i ++)        {            a[i] = s[i] - '0';        }        flag = 0;        memset(vis,0,sizeof(vis));        dfs(0);        if(flag==0)        f=1;    }    if(f==0) printf("TRUE\n");        else printf("BUSTED\n");    }    return 0;}