線段樹直接處理，lazy標記記得下放。每個區間的各種顏色可以用二進制保存，因為最多只有30種顏色，所以用int就行。

      兩個區間合并后的顏色用或運算。

AC代碼：

#include<cstdio>#include<algorithm>using namespace std;const int maxn = 4e5 + 5;struct node{    int L, R;    int color, tag;}t[maxn];void Build(int l, int r, int cur){ //Build the tree    t[cur].L = l; t[cur].R = r;    t[cur].color = t[cur].tag = 1;    if(l == r) return;    int mid = (l + r) / 2;    Build(l, mid, cur << 1);    Build(mid + 1, r, (cur << 1) + 1);}void Update(int l, int r, int c, int cur){    //PRintf("%d %d/n",l,r);    int l1 = t[cur].L, r1 = t[cur].R;    if(l1 == l && r1 == r){        t[cur].color = 1 << (c - 1);        t[cur].tag = 1;        return;    }    if(t[cur].tag){ //Let the lazy tag down        t[(cur << 1) + 1].tag = t[cur << 1].tag = t[cur].tag;        t[(cur << 1) + 1].color = t[cur << 1].color = t[cur].color;    }    int mid = (l1 + r1) / 2;    if(r <= mid) Update(l, r, c, cur << 1);    else if(l >= mid + 1) Update(l, r, c, (cur << 1) + 1);    else {        Update(l, mid, c, cur << 1);        Update(mid + 1, r, c, (cur << 1) + 1);    }    t[cur].color = t[cur << 1].color | t[(cur << 1) + 1].color;    int x = t[cur].color;    t[cur].tag = (x & (x - 1)) ? 0 :1;}int Find(int l, int r, int cur){    int l1 = t[cur].L, r1 = t[cur].R;    if(l1 == l && r1 == r || t[cur].tag) return t[cur].color;    if(t[cur].tag){ //Let the lazy tag down        t[(cur << 1) + 1].tag = t[cur << 1].tag = t[cur].tag;        t[(cur << 1) + 1].color = t[cur << 1].color = t[cur].color;    }    int mid = (l1 + r1) / 2;    if(r <= mid) return Find(l, r, cur << 1);    else if(l >= mid + 1) return Find(l, r, (cur << 1) + 1);    else {        int x = Find(l, mid, cur << 1);        int y = Find(mid + 1, r, (cur << 1) + 1);        return x | y;    }}int main(){    int L, T, Q;    while(scanf("%d%d%d", &L, &T, &Q) == 3){        Build(1, L, 1);        getchar();        char ch;        int a, b, c;        for(int i = 0; i < Q; ++i){            scanf("%c",&ch);            if(ch == 'C') {                scanf("%d%d%d", &a, &b, &c);                if(a > b) swap(a, b);                Update(a, b, c, 1);            }            else {                scanf("%d%d", &a, &b);                if(a > b) swap(a, b);                int x = Find(a, b, 1);                int ans = 0;                while(x > 0){                    if(x & 1) ++ans;                    x >>= 1;                }                printf("%d/n", ans);            }            getchar();        }    }    return 0;}如有不當之處歡迎指出！