题目链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1416

解法：话说这个题目鬼畜了吧，神坑啊。我很快写完交上去wa了，实在改不出来，自己写了数据生成器想和网上的ac代

码拍一下，拍了大概10组随机数据发现答案完全一样啊，这能WA??? 想了很久，乱几把改了改还是WA??? 怒交了一发

网上的ac代码？？？ 返回WA??? 这数据出问题了吧。。。。

附上代码和数据生成器

//BZOJ 1416

#include <bits/stdc++.h>
using namespace std;

const int maxn = 50010;
typedef long long LL;
struct Fraction{
    LL a, b; //a代表分子，b代表分母
    Fraction(){
        a = 0; b = 1;
    }
    void reduction(){
        if(a == 0){
            b = 1;
            return;
        }
        LL gcdnum = __gcd(a, b);
        a /= gcdnum;
        b /= gcdnum;
    }
    Fraction(LL num){ //整数
        a = num; b = 1;
    }
    Fraction(LL x, LL y){
        a = x, b = y;
        this->reduction();
    }
    void operator = (const LL &num){
        a = num; b = 1;
        this -> reduction();
    }
    void operator = (const Fraction &y){
        a = y.a; b = y.b;
        this -> reduction();
    }
    Fraction operator + (const Fraction &y) const{
        LL gcdnum = __gcd(b, y.b);
        Fraction tmp = Fraction(a * (y.b / gcdnum) + y.a * (b / gcdnum) , b / gcdnum * y.b);
        tmp.reduction();
        return tmp;
    }
    Fraction operator + (const LL &y) const{
        return ((*this) + Fraction(y));
    }
    Fraction operator - (const Fraction &y) const{
        return ((*this) + Fraction(-y.a, y.b));
    }
    Fraction operator - (const LL &y) const{
        return ((*this) - Fraction(y));
    }
    Fraction operator * (const Fraction &y) const{
        Fraction tmp = Fraction(a * y.a, b * y.b);
        tmp.reduction();
        return tmp;
    }
    Fraction operator / (const Fraction &y) const{
        return ((*this) * Fraction(y.b, y.a));
    }
    void print(){
       printf("%lld/%lld\n",a,b);
    }
};

int t, n, d, x, y;
long long tot;
int a[maxn];
int main(){
    //freopen("1.txt", "r", stdin);
    //freopen("1.out", "w", stdout);
    Fraction aa;
    tot = 0;
    aa=(1,1);
    scanf("%d%d%d", &t,&n,&d);
    for(int i=1; i<=t; i++){
        scanf("%d", &a[i]);
        tot+=1LL*a[i];
    }
    while(n--){
        long long x,y;
        scanf("%lld%lld",&x,&y);
        aa = aa*Fraction(a[y], tot);
        tot+=d;
        a[y]+=d;
    }
    aa.print();
    return 0;
}

数据生成器：

#include <bits/stdc++.h>
using namespace std;

int main()
{
    //freopen("1.txt", "w", stdout);
    //int t, n, d;
    srand(time(NULL));
    int t = rand()%1000;
    if(t==0) t=1;
    int n = rand()%1000;
    if(n==0) n=10;
    int d=rand()%10;
    if(d==0) d=2;
    printf("%d %d %d\n", t, n, d);
    for(int i = 0; i < t; i++){
        int x = rand()%t;
        if(x==0) x=1;
        printf("%d%c",x,i==n-1?'\n':' ');
    }
    for(int i=1; i<=n; i++){
        int x = rand()%t;
        if(x==0) x=1;
        printf("%d %d\n", i, x);
    }
    return 0;
}