uva 515 - King(差分约时系统）

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题目链接：uva 515 - King

实在不懂什么是差时约分系统，不过大概了解是说建完图之后不能存在负环（既要最短路），如果存在负环的话，两个sum之间就不存在一个稳定的关系。参考题解。

#include <stdio.h>#include <string.h>#include <vector>#include <queue>using namespace std;const int N = 105;const int INF = 0x3f3f3f3f;int n, m, tmp;vector< pair<int, int> > v[N];void init() {scanf("%d", &m);tmp = n + 1;v[tmp].clear();for (int i = 0; i < tmp; i++)v[i].clear(), v[tmp].push_back( make_pair(i, 0) );int s, t, k;char ch[N];for (int i = 0; i < m; i++) {scanf("%d%d%s%d", &s, &t, ch, &k);if (strcmp(ch, "gt") == 0) {v[s + t].push_back( make_pair(s - 1, -k -1) );} else {v[s - 1].push_back( make_pair(s + t, k -1) );}}}bool spfa() {int u, w, s, t;int vis[N], d[N], c[N];queue<int> q;memset(vis, 0, sizeof(vis));memset(c, 0, sizeof(c));memset(d, INF, sizeof(d));d[tmp] = 0; vis[tmp] = 1, c[tmp] = 1;q.push(tmp);while ( !q.empty() ) {u = q.front(); q.pop();vis[u] = 0;t = v[u].size();for (int i = 0; i < t; i++) {s = v[u][i].first, w = v[u][i].second;if (d[s] > d[u] + w) {d[s] = d[u] + w;c[s]++;if (c[s] > tmp + 1) return false;if ( !vis[s] ) {q.push(s);vis[s] = 1;}}}}return true;}int main () {while (scanf("%d", &n) == 1 && n) {init();printf("%s\n", spfa() ? "lamentable kingdom" : "successful conspiracy");}return 0;}