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Create dice-roll-simulation.cpp
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C++/dice-roll-simulation.cpp

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// Time: O(m * n), m is the max of rollMax
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// Space: O(m)
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class Solution {
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public:
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int dieSimulator(int n, vector<int>& rollMax) {
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static const int MOD = 1e9 + 7;
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vector<vector<int>> dp;
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for (int i = 0; i < 6; ++i) {
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dp.emplace_back(rollMax[i]);
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dp[i][0] = 1; // 0-indexed
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}
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while (--n) {
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vector<vector<int>> new_dp;
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for (int i = 0; i < 6; ++i) {
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new_dp.emplace_back(rollMax[i]);
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}
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for (int i = 0; i < 6; ++i) {
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for (int k = 0; k < rollMax[i]; ++k) {
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for (int j = 0; j < 6; ++j) {
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if (i == j) {
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if (k < rollMax[i] - 1) { // 0-indexed
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new_dp[j][k + 1] = (new_dp[j][k + 1] + dp[i][k]) % MOD;
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}
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} else {
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new_dp[j][0] = (new_dp[j][0] + dp[i][k]) % MOD;
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}
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}
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}
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}
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dp = move(new_dp);
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}
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uint64_t result = 0;
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for (const auto& row : dp) {
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const auto& total =
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accumulate(row.cbegin(), row.cend(),
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0ull,
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[&](const auto& a, const auto& b) {
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return (a + b) % MOD;
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});
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result = (result + total) % MOD;
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}
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return result;
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}
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};

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