D

Given a sequence of integers, a1, a2, . . . , an, we define its sign matrix S such that, for 1 ≤ i ≤ j ≤ n, Sij = “ + ” if ai + . . . + aj > 0; Sij = “ − ” if ai + . . . + aj < 0; and Sij = “0” otherwise. For example, if (a1, a2, a3, a4) = (−1, 5, −4, 2), then its sign matrix S is a 4 × 4 matrix: 1 2 3 4 1 − + 0 + 2 + + + 3 − − 4 + We say that the sequence (−1, 5, −4, 2) generates the sign matrix. A sign matrix is valid if it can be generated by a sequence of integers. Given a sequence of integers, it is easy to compute its sign matrix. This problem is about the opposite direction: Given a valid sign matrix, find a sequence of integers that generates the sign matrix. Note that two or more different sequences of integers can generate the same sign matrix. For example, the sequence (−2, 5, −3, 1) generates the same sign matrix as the sequence (−1, 5, −4, 2). Write a program that, given a valid sign matrix, can find a sequence of integers that generates the sign matrix. You may assume that every integer in a sequence is between −10 and 10, both inclusive. Input The input consists of T test cases. The number of test cases T is given in the first line of the input. Each test case consists of two lines. The first line contains an integer n (1 ≤ n ≤ 10), where n is the length of a sequence of integers. The second line contains a string of n(n + 1)/2 characters such that the first n characters correspond to the first row of the sign matrix, the next n − 1 characters to the second row, . . ., and the last character to the n-th row. Output For each test case, output exactly one line containing a sequence of n integers which generates the sign matrix. If more than one sequence generates the sign matrix, you may output any one of them. Every integer in the sequence must be between −10 and 10, both inclusive. Sample Input 3 4 -+0++++--+ 2 +++ 5 ++0+-+-+--+-+-- Sample Output -2 5 -3 1 3 4 1 2 -3 4 -5

拓扑排序:把sum(i,j)考虑成pre[j] - pre[i-1]的形式,然后可以建立图的关系,进行拓扑排序,从大到小,每一个拓扑序后面的点都比前面小,所以每当在拓扑排序里遇到该点(说明当前值比它大),都将遇到的点的sum 减一

注意i前缀序列是n+1项,【0,n】

#include<iostream>
#include<cstdio> #include<queue> #include<algorithm> #include<cstring> #include<string> using namespace std; #define MAXN 14 #define N 100 int in[MAXN], g[MAXN][MAXN]; int sum[MAXN]; char str[N]; int main() { int T, n; scanf("%d", &T); while (T--) { memset(g, 0, sizeof(g)); memset(in, 0, sizeof(in)); memset(sum, 0, sizeof(sum)); scanf("%d", &n); scanf("%s", str); int pos = 0; for (int i = 1; i <= n; i++) { for (int j = i; j <= n; j++) { char c; c = str[pos++]; if (c == '+') { g[j][i-1] = 1; in[i - 1]++; } else if(c == '-') { g[i - 1][j] = 1; in[j]++; } } } queue<int> q; while (!q.empty()) q.pop(); for (int i = 0; i <= n; i++) if (!in[i]) q.push(i); while (!q.empty()) { int tmp = q.front(); q.pop(); for (int i = 0; i <= n; i++)//必须从0开始 { if (g[tmp][i] == 1) { sum[i]--; if (--in[i] == 0) q.push(i); } } } for (int i = 1; i <= n; i++) { printf("%d", sum[i] - sum[i - 1]); if (i != n)printf(" "); else printf(" "); } } }
原文地址:https://www.cnblogs.com/joeylee97/p/7301180.html