[刷题]算法竞赛入门经典(第2版) 6-1/UVa673 6-2/UVa712 6-3/UVa536

这三题比较简单，只放代码了。

---

题目：6-1 UVa673 - Parentheses Balance

//UVa673 - Parentheses Balance
//Accepted 0.000s
//#define _XIENAOBAN_
#include<iostream>
using namespace std;

int N;
char line[130];
bool st[130];
bool cal() {
    if (*line == '\0') return true;
    auto *p = line;
    auto *top = st;
    do {
        switch (*p)
        {
        case '(': *++top = false;break;
        case '[': *++top = true;break;
        case ')':
            if (top == st || *top) return false;
            --top;
            break;
        default:
            if (top == st || !*top) return false;
            --top;
            break;
        }
    } while (*++p != '\0');
    return top == st;
}


int main()
{
#ifdef _XIENAOBAN_
#define gets(T) gets_s(T, 129)
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif

    scanf("%d",&N);
    getchar();
    while (N--) {
        gets(line);
        cout << (cal() ? "Yes" : "No") << '\n';
    }

    return 0;
}

---

题目：6-3 UVa712 - S-Trees

//UVa712 - S-Trees
//Accepted 0.000s
//#define _XIENAOBAN_
#include<iostream>
using namespace std;

int N(0);
int n, m, ord[10], run[10], val[130];

int main()
{
#ifdef _XIENAOBAN_
#define gets(T) gets_s(T, 129)
    freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
#endif

    while (scanf("%d", &n) != EOF && n != 0) {
        printf("S-Tree #%d:\n", ++N);
        int num(1 << n);
        for (int i(1);i <= n;++i) {
            while (getchar() != 'x');
            ord[i] = getchar() - 48;
        }
        while (getchar() != '\n');
        for (int i(0);i < num;++i)
            val[i] = getchar() - 48;
        scanf("%d", &m);
        for (int i(0);i < m;++i) {
            while (getchar() != '\n');
            for (int j(1);j <= n;++j)
                run[j] = getchar() - 48;
            int ans(1);
            for (int j(1);j <= n;++j)
                ans = (ans << 1) + run[ord[j]];
            printf("%d", val[ans - num]);
        }
        printf("\n\n");
    }
    return 0;
}

---

题目：6-3 UVa536 - Tree Recovery

//UVa536 - Tree Recovery
//Accepted 0.000s
//#define _XIENAOBAN_
#include<iostream>
#include<cstring>
using namespace std;

char pre[30], in[30];

void cal(char *pre, char *in, int len) {
    int root(0);
    while (*(in + root) != *pre) ++root;
    if (root) cal(pre + 1, in, root);
    if (len - root - 1) cal(pre + root + 1, in + root + 1, len - root - 1);
    printf("%c", *pre);
}


int main()
{
#ifdef _XIENAOBAN_
#define gets(T) gets_s(T, 129)
    freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
#endif

    while (scanf("%s%s", pre, in) != EOF) {
        cal(pre, in, strlen(in));
        puts("");
    }
    return 0;
}