【HDOJ】1502 Regular Words

大数+DP，感觉这个DP有点儿抽象，而且这个是大数，wa了很多次。

#include <stdio.h>

#define MAXNUM 61
#define MAXLEN 100

typedef struct {
    char val[MAXLEN];
} src_st;

src_st dp[MAXNUM][MAXNUM][MAXNUM];

void BigIntAdd(src_st *a, src_st *b) {
    int i;

    for (i=; i<MAXLEN; ++i) {
        a->val[i] += b->val[i];
        if (a->val[i] >= ) {
            a->val[i+]++;
            a->val[i] -= ;
        }
    }
}

int main() {
    int i, j, k;

    dp[][][].val[] = ;

    for (i=; i<MAXNUM; ++i)
        for (j=; j<=i; ++j)
            for (k=; k<=j; ++k) {
                memset(dp[i][j][k].val, , sizeof(dp[i][j][k].val));
                if (i->=j)
                    BigIntAdd(&dp[i][j][k].val, &dp[i-][j][k].val);
                if (j->=k)
                    BigIntAdd(&dp[i][j][k].val, &dp[i][j-][k].val);
                if (k)
                    BigIntAdd(&dp[i][j][k].val, &dp[i][j][k-].val);
            }

    while (scanf("%d", &k) != EOF) {
        j = ;
        for (i=MAXLEN-; i>=; i--) {
            if (j== && dp[k][k][k].val[i] == )
                continue;
            if (j== && dp[k][k][k].val[i] != )
                j = ;
            printf("%c", dp[k][k][k].val[i]+'');
        }
        printf("\n\n");
    }

    return ;
}