sgu 138

自己猜测了一下  按比赛次数 从大到小排  然后类似于模拟 先排胜的场次 当只剩一场 将它定义为败

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <map>
#include <set>
#include <stack>
#include <vector>
#include <sstream>
#include <string>
#include <cstring>
#include <algorithm>
#include <iostream>
#define maxn 100010
#define INF 0x7fffffff
#define inf 10000000
#define MOD 1000000007
#define ull unsigned long long
#define ll long long
using namespace std;

struct node
{
    int id, x;
    bool operator < (const node& p) const
    {
        return x > p.x;
    }
};
node pp[110];
int win[maxn], lose[maxn];

void solve(int sum)
{
    int j = 0;
    for(int i =0 ; i < sum; ++ i)
    {
        while(!pp[j].x) j++;
        if(pp[j].x > 1)
        {
            win[i] = pp[j].id;
            pp[j].x--;
        }
        else if(pp[j].x == 1)
        {
            lose[i] = pp[j].id;
            pp[j].x--;
            j++;
            win[i] = pp[j].id;
            pp[j].x--;
        }
    }
    j = 0;
    for(int i =0 ; i < sum; ++ i)
    {
        if(lose[i]) continue;
        while(!pp[j].x) j++;
        if(pp[j].x > 1)
        {
            lose[i] = pp[j].id;
            pp[j].x--;
        }
        else if(pp[j].x == 1)
        {
            lose[i] = pp[j].id;
            pp[j].x--;
            j++;
        }
    }
}

int main()
{
    int n;
    while(scanf("%d", &n) == 1)
    {
        int sum = 0;
        for(int i = 0; i < n; ++ i)
        {
            scanf("%d", &pp[i].x);
            pp[i].id = i+1;
            sum += pp[i].x;
        }
        sort(pp, pp+n);
        memset(win, 0, sizeof(win));
        memset(lose, 0, sizeof(lose));
        sum /= 2;
        solve(sum);
        printf("%d\n", sum);
        for(int i = 0; i < sum; ++ i)
            printf("%d %d\n", win[i], lose[i]);
    }
    return 0;
}