1652. Defuse the Bomb

Violence

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class Solution {
    public int[] decrypt(int[] code, int k) {
        int[] ans = new int[code.length];

        for (int i = 0; i < ans.length; i++) {
            if (k < 0) {
                for (int j = k; j < 0; j++) {
                    // 注意此处 j 是负数，所以下方计算索引时使用的符号为加号
                    ans[i] += code[(i + code.length + j) % code.length];
                }
            } else if (k > 0) {
                for (int j = 1; j <= k; j++) {
                    ans[i] += code[(i + j) % code.length];
                }
            }
        }

        return ans;
    }
}

Prefix Sum

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class Solution {
    public int[] decrypt(int[] code, int k) {
        int n = code.length;

        int[] prefixSums = new int[2 * n + 1];
        for (int i = 0; i < 2 * n; i++) {
            prefixSums[i + 1] = prefixSums[i] + code[i % n];
        }

        int[] res = new int[n];
        for (int i = 0; i < n; i++) {
            if (k < 0) {
                res[i] = prefixSums[i + n] - prefixSums[i + n + k];
            } else if (k > 0) {
                res[i] = prefixSums[i + 1 + k] - prefixSums[i + 1];
            }
        }
        return res;
    }
}

References

1652. Defuse the Bomb