UVA 10157 Expressions

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#include <cstdio>#include <cstring>using namespace std;const int LEN=100;const int NMAX=300;const int DMAX=150;int f[NMAX+1][DMAX+1][LEN];bool vis[NMAX+1][DMAX+1];void add(int a[],int b[]){    int c = 0;    for(int i = 0; i < LEN; ++i){        int n = (c+a[i]+b[i]) % 10;        c = (c+a[i]+b[i]) / 10;        a[i] = n;    }}void sub(int a[],int b[]){    int c = 0;    for (int i = 0; i < LEN; i++){        a[i] = a[i] - b[i] + c;        if (a[i] < 0){            a[i] += 10;            c = -1;        }        else c = 0;    }}void mul(int a[],int b[]){    int c[LEN];    memset(c,0,sizeof(c));    int I = LEN;    while(--I >= 0 && a[I] == 0);   //去除前导0    ++I;    int K = LEN;    while(--K >= 0 && b[K] == 0);    ++K;    for(int i = 0; i < I; ++i)        for(int k = 0; k < K && i+k < LEN; ++k)            c[i+k] += a[i]*b[k];    int d = 0;    for(int i = 0; i < LEN; ++i)    {        int n = (d + c[i]) % 10;        d = (d + c[i]) / 10;        c[i] = n;    }    memcpy(a,c,sizeof(c));}void print(int a[]){    int i = LEN;    while(--i > 0 && a[i]==0);    for (int j = i; j >= 0; j--)        printf("%d",a[j]);    printf("\n");}void cal(int n,int d){    if(vis[n][d])        return;    vis[n][d] = 1;    if(n % 2 == 1)        return;    if(n == 0){        f[n][d][0]=1;        return;    }    if(d == 0)        return;    int t[LEN];    for(int i = 0; i < n; i+=2){        cal(i,d);        cal(n-2-i,d-1);        memcpy(t,f[i][d],sizeof(t));        mul(t,f[n-2-i][d-1]);        add(f[n][d],t);    }}int main(){    int n,d;    while(scanf("%d%d",&n,&d)==2){        if(d==0 && n==0){            printf("1\n");            continue;        }        else if(d == 0){            printf("0\n");            continue;        }        else if(n == d*2){            printf("1\n");            continue;        }        memset(f,0,sizeof(f));        memset(vis,0,sizeof(vis));        cal(n,d);    //计算深度不超过d的可能        cal(n,d-1);        int ans[LEN];        memcpy(ans,f[n][d],sizeof(ans));        sub(ans,f[n][d-1]);        print(ans);    }    return 0;}