uvaLive 3713

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题目链接
#include <cstdio>#include <cstring>#include <vector>using namespace std;#define N 200010#define INF 0x3f3f3f3fstruct TwoSAT{    int n, c;    vector<int> G[N];    bool mark[N];    int S[N];    bool dfs(int x) {        if (mark[x ^ 1]) return false;        if (mark[x]) return true;        mark[x] = true;        S[c++] = x;        for (int i = 0; i < G[x].size(); i++)            if (!dfs(G[x][i])) return false;        return true;    }    void init(int n) {        this->n = n;        for (int i = 0; i < 2 * n; i++)            G[i].clear();        memset(mark, 0, sizeof(mark));    }    //x == xval or y == yval     //这里的值是x为真或者y为真，若想两条件不同时成立，可以传递进非x和非y,即x^1 y^1    void add_clause(int x, int xval, int y, int yval) {        x = x * 2 + xval;        y = y * 2 + yval;        G[x^1].push_back(y);        G[y^1].push_back(x);    }    bool solve() {        for (int i = 0; i < 2 * n; i += 2) {            if (!mark[i] && !mark[i + 1]) {                c = 0;                if (!dfs(i)) {                    while (c > 0) mark[S[--c]] = false;                    if (!dfs(i + 1)) return false;                }            }        }        return true;    }};TwoSAT solver;int age[N], ave, n, m;void solve(){    if(!solver.solve())        printf("No solution.\n");    else    {        for(int i = 0; i < n; i++)            if(age[i] >= ave)                printf("%c\n", !solver.mark[i * 2] ? 'A' : 'C');            else                printf("%c\n", !solver.mark[i * 2] ? 'B' : 'C');    }}int main(){    while(~scanf("%d%d", &n, &m) && n + m)    {        solver.init(n);        ave = 0;        for(int i = 0; i < n; i++) {                scanf("%d", age + i);                ave += age[i];        }        ave = (ave + n - 1) / n;        int u, v;        for(int i = 0; i < m; i++)        {            scanf("%d%d", &u, &v);            u--, v--;            if((age[u] >= ave && age[v] >= ave) || (age[u] < ave && age[v] < ave))            {                solver.add_clause(u, 1, v, 1);                solver.add_clause(u, 0, v, 0);            }            else            {                solver.add_clause(u, 1, v, 1);            }        }        solve();    }    return 0;}
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