2018 Multi-University Training Contest 2 1007 hdu 6315 Naive Operations[线段树瞎搞]

题目链接

思路： 维护区间最小值和当前答案。

区间最小值初始化位b[i], 每次更新将其-1， 为0时答案+1。

#include <cstdio>
#include <algorithm>
#include <cstring>
#define ms(x) memset(x, 0, sizeof(x))
using namespace std;

#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
const int MAXN = 1e5+3;
const int INF = 0x3f3f3f3f;
int b[MAXN<<2];
int SUM[MAXN<<2], MIN[MAXN<<2];
int lazy[MAXN<<2];

void PushUp(int rt) {
	SUM[rt] = SUM[rt<<1] + SUM[rt<<1|1];
	MIN[rt] = min(MIN[rt<<1], MIN[rt<<1|1]);
}

void PushDown(int rt) {
	if(lazy[rt]) {
		lazy[rt<<1] += lazy[rt];
		lazy[rt<<1|1] += lazy[rt];
		MIN[rt<<1] -= lazy[rt];
		MIN[rt<<1|1] -= lazy[rt];
		lazy[rt] = 0;
	}
}

// 以下的 l, r, rt 带入 1, n, 1
void Build(int l, int r, int rt) {
	lazy[rt] = 0;
	if(l == r) {
		// 初始化树为 0 的写法
		MIN[rt] = b[l];
		SUM[rt] = 0;
		return;
	}
	int m = (l + r) >> 1;
	Build(lson);
	Build(rson);
	PushUp(rt);
}

void Update(int L, int R, int l, int r, int rt) {
	if(L<=l && r<=R) {
		lazy[rt] += 1;
		MIN[rt] -= 1;
		return;
	}
	PushDown(rt);
	int m = (l + r) >> 1;
	if(L <= m) Update(L, R,  lson);
	if(R > m) Update(L, R, rson);
	PushUp(rt);
}
void dfs(int l, int r, int rt){
    if(MIN[rt]!=0) return ;
    if(l==r){
        MIN[rt] = b[l];
        SUM[rt]++;
        return ;
    }
    PushDown(rt);
	int m = (l + r) >> 1;
    dfs(lson);
    dfs(rson);
    PushUp(rt);
}

// 求区间 L~R 的和
int QuerySum(int L, int R, int l, int r, int rt) {
	if(L<=l && r<=R) return SUM[rt];
	PushDown(rt);
	int m = (l + r) >> 1;
	int ret = 0;
	if(L <= m) ret += QuerySum(L, R, lson);
	if(R > m) ret += QuerySum(L, R, rson);

	return ret;
}

// 求区间 L~R 的最小值
int QueryMin(int L, int R, int l, int r, int rt) {
	if(L<=l && r<=R) return MIN[rt];
	PushDown(rt);
	int m = (l + r) >> 1;
	int ret = INF;
	if(L <= m) ret = min(ret, QueryMin(L, R, lson));
	if(R > m) ret = min(ret, QueryMin(L, R, rson));

	return ret;
}

int main(){
    int n, m;
    while(scanf("%d%d", &n, &m)!=EOF){
    ms(lazy);
    for(int i=1;i<=n;i++){
        scanf("%d", &b[i]);
    }
    Build(1,n,1);
    while(m--){
        char s[10];
        int l, r;
        scanf("%s%d%d",s, &l, &r);
        if(s[0] == 'a'){
            Update(l,r,1,n,1);
            dfs(1,n,1);
        }
        else{
            printf("%d\n", QuerySum(l,r,1,n,1));
        }
    }
    }
    return 0;
}