POJ2201 Cartesian Tree (cartesian tree)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)
#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)
#define Max(a,b) ((a) > (b) ? (a) : (b))
#define Min(a,b) ((a) < (b) ? (a) : (b))
#define Fill(a,b) memset(a, b, sizeof(a))
#define Swap(a,b) a^=b^=a^=b
#define ll long long
#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")
#define	D_e(x)	cout << #x << " = " << x << endl

#else

#define D_e_Line ;

#endif

struct ios{
    template<typename ATP>ios& operator >> (ATP &x){
        x = 0; int f = 1; char c;
        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;
        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();
        x*= f;
        return *this;
    }
}io;
using namespace std; 

const int N = 50007;

struct node{
	int l,r,fa,id;
	int val,pri;
	bool operator < (const node &com)const{
		return val < com.val;
	}
}t[N],ans[N];

inline void Insert(int rt){
	int tmp;
	for(tmp = rt - 1; t[tmp].pri > t[rt].pri; tmp = t[tmp].fa);
	t[rt].l = t[tmp].r;
	t[t[tmp].r].fa = rt;
	t[rt].fa = tmp;
	t[tmp].r = rt;
}

int vis[30007];
int main(){
    int n;
    while(scanf("%d", &n) != EOF){
        Fill(vis, false);
        int flag = true;
	    R(i,0,n){
	        t[i].l = t[i].r = t[i].fa = 0;
	        t[i].w = -0x7fffffff;
	    }

        R(i,1,n){
            scanf("%d%d", &t[i].val, &t[i].w);
            t[i].id = i;
            if(vis[t[i].val])
                flag = false;
            else
                vis[t[i].val] = true;
        }
        if(!flag){
        	printf("NO\n");
        	continue;
        }
        printf("YES\n");

		sort(t + 1, t + n + 1);

        R(i,1,n) Insert(i);

        R(i,1,n){
            if(!t[i].l)
                ans[t[i].id].l = 0;
            else
                ans[t[i].id].l = t[t[i].l].id;
            if(!t[i].r)
                ans[t[i].id].r = 0;
            else
                ans[t[i].id].r = t[t[i].r].id;
            if(!t[i].fa)
                ans[t[i].id].fa = 0;
            else
                ans[t[i].id].fa = t[t[i].fa].id;
        }

        R(i,1,n)
            printf("%d %d %d\n", ans[i].fa, ans[i].l, ans[i].r);
    }

    return 0;
}