UVA 1423 Guess 【拓扑排序】

题目链接：http://acm.hust.edu.cn/vjudge/problem/visitOriginUrl.action?id=36239

题意：给你序列的区间和的正负，要求构造一组序列满足条件。
转换为前缀和，进行拓扑序列。

代码：

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<string.h>
#include<queue>

using namespace std;

char s[123];
int n;
int sum[110];
int du[110], is[15][15];

void toposort()
{
    queue<int> que;
    while (!que.empty()) que.pop();
    for (int i = 0; i <= n; i++)
        if (du[i] == 0) que.push(i);

    int tmp = 0;

    while (!que.empty())
    {
        int t = que.front(); que.pop();
        tmp++;
        for (int i = 0; i <= n; i++)
        {
            if (is[t][i])
            {
                du[i]--;
                if (du[i] == 0)
                {
                    que.push(i);
                    sum[i] = tmp;
                }
            }
        }
    }
    return;
}

int main()
{
    int t;
    scanf("%d",&t);
    while (t--)
    {
        scanf("%d",&n);
        scanf(" %s", s);
        memset(sum, 0, sizeof(sum));
        memset(du, 0, sizeof(du));
        memset(is, 0, sizeof(is));

        int pos = 0;
        for (int i = 1; i <= n; i++)
            for (int j = i; j <= n; j++)
            {
                if (s[pos] == '+')
                {
                    is[i - 1][j] = 1;
                    du[j]++;
                }
                else if (s[pos] == '-')
                {
                    is[j][i - 1] = 1;
                    du[i - 1]++;
                }
                pos++;
            }
        toposort();
        for (int i = 1; i <= n; i++)
            printf("%d%c", sum[i] - sum[i - 1], i == n ? '\n' : ' ');
    }
    return 0;
}