2014 UESTC Training for Graph Theory F

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HAVEL定理的应用
利用优先队列模拟该过程
取出序列中最大值dmax，若dmax大于n-1,无解退出。否则取出剩下n-1个元素中前dmax大的dmax个元素，把这些元素依次减1后放回序列中，dmax舍弃，n=n-1

如果出现负数那么则无解

#include <map>#include <set>#include <list>#include <cmath>#include<cctype>#include <ctime>#include <deque>#include <stack>#include <queue>#include <cstdio>#include <string>#include <vector>#include <cstdlib>#include <cstring>#include <iostream>#include <algorithm>#define LL long long#define PI 3.1415926535897932626using namespace std;int gcd(int a, int b){return a % b == 0 ? b : gcd(b, a % b);}#define MAXN 100005int sum;int Count;int N;int src[MAXN];struct node{    int data;    bool operator < (const node &a)    {        return data>a.data;    }};priority_queue<int>q;void slove(){    sum=0;    int tmp=0;    bool flag=false;    scanf("%d",&N);    while (!q.empty()) q.pop();    for (int i=0;i<N;i++)    {        scanf("%d",&tmp);        sum+=tmp;        q.push(tmp);    }    //for (int i=0;i<N;i++) printf("%d ",src[i]);putchar('\n');    if (sum%2!=0) {printf("NO\n");return;}    while (!q.empty())    {        int cas=0;        int tmp=q.top();q.pop();        if (tmp>=N) {flag=true;break;}        for (int i=1;i<=tmp;i++)        {            if (q.empty()) break;            src[cas]=q.top();q.pop();            src[cas]--;            if (src[cas]<0) {flag=true;break;}            cas++;        }        if (flag) break;        for (int i=0;i<cas;i++)            q.push(src[i]);        N--;    }    if  (!flag)printf("YES\n");    else printf("NO\n");}int main(){    int T;    scanf("%d",&T);    while (T--)        slove();    return 0;}

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