# UVALive4255-Guess (topological sorting)

Source: Internet
Author: User

For a sequence A1, a2... an, we can calculate a symbol matrix s, where SIJ is the positive and negative signs of AI ++ AJ. Given the symbol matrix, a corresponding sequence must be output.

Train of Thought: use the technique of consecutive and converting to the difference between the prefix and the prefix as a vertex, so that we can establish the relationship between the edge and the level, and then use the topological sorting to solve the problem, first, a vertex with an inbound degree of 0 is deleted, and related edges are operated cyclically.

Code:

`#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 30;char str[MAXN * 10];int in[MAXN], vis[MAXN], g[MAXN][MAXN], sum[MAXN];int n;void toposort() {    int d = 0, low = -10;    while (d <= n) {        memset(vis, 0, sizeof(vis));        for (int i = 0; i <= n; i++) {            if (in[i] == 0) {                sum[i] = low;                 in[i] = -1;                vis[i] = 1;                d++;            }        }        low++;        for (int i = 0; i <= n; i++) {            if (vis[i]) {                for (int j = 0; j <= n; j++)                     if (g[i][j])                        in[j]--;             }        }    } }int main() {    int cas;    scanf("%d", &cas);    while (cas--) {        scanf("%d", &n);               scanf("%s", str);        memset(in, 0, sizeof(in));        memset(g, 0, sizeof(g));        memset(sum, 0, sizeof(sum));        int cnt = 0;        for (int i = 1; i <= n; i++) {            for (int j = i; j <= n; j++) {                if (str[cnt] == '+') {                    in[j]++;                    g[i - 1][j] = 1;                 }                 else if (str[cnt] == '-') {                    in[i - 1]++;                      g[j][i - 1] = 1;                }                cnt++;            }        }                 toposort();        for (int i = 1; i <= n; i++) {            if (i == 1)                printf("%d", sum[i] - sum[i - 1]);            else                 printf(" %d", sum[i] - sum[i - 1]);         }        printf("\n");    }    return 0;}`

UVALive4255-Guess (topological sorting)

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