zoj1610 Count the Colors 线段树

题目链接在这里

题目描述:

在一条直线上画不同颜色的线段,给出各线段的起点、终点和颜色,求画完之后,最终会有几种颜色,每个颜色有多少条线段。

思路分析:

我们用线段树保存各点的颜色,区间更新,最后query一下就好。

注意题目给的是线段的起点和终点,是连续的。如果想用离散的表示的话,就让起点+1,代表一段。

代码如下:

非结构体:

#include 
#include 
#include 
#include 
#include 
#define rep(i, n) for(int i = 0; i < n; ++i)
#define clr(x) memset(x, 0, sizeof(x))
#define rl (rt << 1)
#define rr (rt << 1 | 1)
#define llen (tree[rl].r - tree[rl].l + 1)
#define rlen (tree[rr].r - tree[rr].l + 1)
using namespace std;

const int MaxN = 10010;

int val[MaxN << 2];
int n, last;
map ma;

void pushdown(int rt){
    if(val[rt] != -1){
        val[rl] = val[rr] = val[rt];
        val[rt] = -1;
    }
}

void update(int l, int r, int rt, int L, int R, int w){
    if(L <= l && r <= R){
        val[rt] = w;
        return;
    }
    pushdown(rt);
    int mid = (l + r) >> 1;
    if(L <= mid)    update(l, mid, rl, L, R, w);
    if(R > mid)     update(mid + 1, r, rr, L, R, w);
}

void query(int l, int r, int rt){
    if(l == r){
        if(val[rt] != -1 && last != val[rt]){
            ++ma[val[rt]];
        }
        last = val[rt];
        return;
    }
    pushdown(rt);
    int mid = (l + r) >> 1;
    query(l, mid, rl);
    query(mid + 1, r, rr);
}

int main(){
    while(~scanf("%d", &n)){
        memset(val, -1, sizeof(val));
        ma.clear();

        int a, b, c;
        rep(i, n){
            scanf("%d %d %d", &a, &b, &c);
            if(a < b)   update(1, 8000, 1, a + 1, b, c);
        }
        last = -1;
        query(1, 8000, 1);
        map::iterator iter;
        for(iter = ma.begin(); iter != ma.end(); ++iter){
            printf("%d %d\n", iter->first, iter->second);
        }
        putchar('\n');
    }
    return 0;
}

结构体:

#include 
#include 
#include 
#include 
#include 
#define rep(i, n) for(int i = 0; i < n; ++i)
#define clr(x) memset(x, 0, sizeof(x))
#define rl (rt << 1)
#define rr (rt << 1 | 1)
#define llen (tree[rl].r - tree[rl].l + 1)
#define rlen (tree[rr].r - tree[rr].l + 1)
using namespace std;

const int MaxN = 10010;

struct Node{
    int l, r, mid;
    int mark;
}tree[MaxN << 2];

int n, last;
map ma;

void pushdown(int rt){
    if(tree[rt].mark != -1){
        tree[rl].mark = tree[rr].mark = tree[rt].mark;
        tree[rt].mark = -1;
    }
}

void build(int l, int r, int rt){
    tree[rt].l = l;
    tree[rt].r = r;
    tree[rt].mark = -1;
    tree[rt].mid = (l + r) >> 1;
    if(l == r)  return;
    build(l, tree[rt].mid, rl);
    build(tree[rt].mid + 1, r, rr);
}

void update(int l, int r, int rt, int w){
    if(l <= tree[rt].l && tree[rt].r <= r){
        //printf("l:%d, r:%d, mark:%d\n", tree[rt].l, tree[rt].r, w);
        tree[rt].mark = w;
        return;
    }
    pushdown(rt);
    /*if(l <= tree[rt].mid)   update(l, tree[rt].mid, rl, w);
    if(tree[rt].mid < r)    update(tree[rt].mid + 1, r, rr, w);*/
    if(r <= tree[rt].mid)   update(l, r, rl, w);
    else if(l > tree[rt].mid)   update(l, r, rr, w);
    else{
        update(l, tree[rt].mid, rl, w);
        update(tree[rt].mid + 1, r, rr, w);
    }
}

void query(int l, int r, int rt){
    if(l == r){

        if(tree[rt].mark != -1 && tree[rt].mark != last){
            ma[tree[rt].mark]++;
        }
        last = tree[rt].mark;
        return;
    }
    pushdown(rt);
    query(l, tree[rt].mid, rl);
    query(tree[rt].mid + 1, r, rr);
}

int main(){
    while(~scanf("%d", &n)){
        ma.clear();
        build(1, 8000, 1);
        int x, y, z;
        rep(i, n){
            scanf("%d %d %d", &x, &y, &z);
            if(x < y)   update(x + 1, y, 1, z);
        }
        query(1, 8000, 1);
        map:: iterator iter;
        //printf("map size:%d\n", ma.size());
        for(iter = ma.begin(); iter != ma.end(); ++iter)
            printf("%d %d\n", iter->first, iter->second);
        putchar('\n');
    }
    return 0;
}

 

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